Diamonds

come multi-stranded or plaited, among other themes or designs. If you are looking forward to getting a diamond jewelry eternity ring—whether as a wedding or engagement, for purely personal satisfaction, or a major investment—take note of its special characteristics aside from carefully examining the 4Cs—the cut, clarity, color, and carat weight.

In a jewelry store, two diamonds may look alike but they can be very different and just like two diamonds of equal size that have very different values. The four qualities of a diamond namely color, clarity, cut and carat weight determine the real value of the gem you are looking for. These standards are also applicable to most gemstones.

Usually, a full diamond eternity ring costs twice or thrice as much than the half eternity because it has more diamonds. More and more people—especially women—focus in buying half diamond eternity rings that have stones concentrated in the “head” or front of the ring because they can easily be sized compared to full eternity rings, more comfortable to wear, and less expensive.

Bear in mind that square, oblong and round stones are excellent choices for diamond eternity rings because of its continuity.

Don’t forget to compare prices. Diamond eternity rings need not always be expensive. If you have found a design that you really admire in a specific jewelry store or an online jeweler, try looking in other stores because they might be selling the same product

with the same specifications for a lesser price. Make sure that you at least have a minor comparison of prices from several different jewelers before you finally buy that princess cut diamond engagement ring.

Check and double-check the bill of sale carefully. After buying your dream diamond eternity ring, make sure that everything about the ring is fully described in written from and explained to you by the jeweler. This content is provided by Low Jeremy and may be used only in its entirety with all links included.

Author  Low Jeremy For more info on Diamond Ring, please visit http://diamond-ring.articlekeep.com
 

A Collection of DIAMOND CRYSTALS with Notes on the Science, History, and Worldwide Localities of Diamonds

Natural diamond crystals are among the most elegant and charismatic of mineralogical collectibles, but they are relatively rare in collections because of their high value as gemstones and diamond jewelry, their typically rather small size and their limited availability outside of the gem trade. Diamond jewelry also represent a rich and extensive cultural history, a broad geographical distribution, and a fascinating geological history still being puzzled out by researchers.
 

Introduction

Diamonds have been found on every continent in the world, with the possible exception of Antarctica, and have been mined from hundreds of deposits worldwide since at least 800 B.C. Enormous stockpiles are held in reserve by DeBeers, the preeminent clearinghouse for world diamonds, and by the Russian Diamond Fund. Diamond can hardly be said to be a rare mineral, despite its traditionally high market value. Despite this seeming abundance of diamonds over the centuries, and the presence of at least token crystals in many 18th and 19th-century mineral collections (some of which are illustrated here for comparison), relatively few collectors, especially in recent times, have ever attempted to specialize in the species. One of the early diamond specialists was the British collector Sir Abraham Hume (1749-1838), whose fine collection of 107 diamond crystals was cataloged by Count de Bournon in 1815. Another early British collector, Charles Hampden Turner (whose mineral collection was assembled for him by the mineral dealer Henry Heuland), possessed 109 examples of diamond. Armand Levy, who prepared Turner's published collection catalog in 1838, remarked that it was impossible to identify the locality for any given diamond crystal based on its habit alone, and so localities were generally not cited in the catalog, but Levy guessed that most of Turner's diamond crystals were probably from Brazil. The extravagant Ecuadorean collector in Paris, Don Pedro Davilla (ca. 17101775), had a mere 16 diamond crystals in his enormous collection of over 8,000 total specimens. The Austrian banker and businessman Jacob Friedrich von der Null, whose huge mineral collection, curated by the prominent mineralogist Friedrich Mohs, was considered to be the best in Vienna, owned 36 diamond crystals (Mohs, 1804). Also in Austria, Ignaz von Born assembled a suite of nine crystals for Mile. Eleanore de Raab in 1791. In the 20th century, Paul seel (1904-1982) assembled a collection of several hundred diamond crystals, each of which "illustrated some morphological fact" (Desautels, 1970).

It was considered by Paul Desautels to be the finest and largest collection of diamond crystals then in existence-and considering his authoritative knowledge of collections worldwide, we can safely accept his judgment. Such collections remain rare today, both because of the high unit cost of good specimens and because the international diamond market is not set up for the distribution of collector-quality uncut crystals. Rough gem-quality diamonds are normally sold only in parcels which cannot be cherry-picked for individual pieces. These parcels are always purchased (usually in Amsterdam) by commercial cutters or by dealers in abrasives, who have no interest in or awareness of diamond crystals as       Photo by jordanrich1
specimens. Therefore the acquisition of collector-quality crystals normally requires the help of someone who is either involved in the commercial end of the diamond trade or who has especially good personal connections in Amsterdam, or both.

A 603 Karat Diamond comes from the Letseng Mine in Lesotho - South Africa- named the "Lesotho Promise".

Recently the Mineralogical Record was given access to a remarkable private collection of diamond crystals. The specimens were acquired by dealers Jack Greenspan and David New over the last 20 years or so. Jack filtered his specimens out of commercial lots purchased for his business in abrasives and saw blades; Dave got his through personal connections with diamond merchants in Amsterdam, who were willing to set aside for him a particularly nice single crystal every once in a while. The private collector who acquired the specimens from these gentlemen was thereby able to assemble an extraordinary diamond collection. Since such a collection is so unusual, we thought that Mineralogical Record readers would like an opportunity to see the specimens and learn something about the geology, cultural contexts and mining histories of the localities represented.

The crystal forms of the diamonds cover a familiar range: there are simple octahedrons, cubes and dodecahedrons, and there are combinations of these; there are single crystals and clusters of crystals, and there are the characteristic, flattened triangular shapes of "made" spinel-law twins. Some of the crystal faces are convex to varying degrees, some are slightly rough, and inspection with a loupe reveals growth trigons on some. A few crystals are highly lustrous and gemmy while others are duller; inclusions may or may not be naked-eye visible.

The physical appearance of diamonds, even large ones, is predictable in many ways, and yet their historical/cultural and even geological histories always have a special fascination. We are talking, after all, about diamonds: adamas was the Greek root word, always carrying connotations of magic powers, invincible strength and the workings of strong, brazen gods.
Before looking specifically at the localities for the 52 diamonds pictured here from the collection, a brief historical overview of diamond mining and a summary of the exotic geological "story" that all localities have in common is in order.

Some HISTORY

Very few modern mineral collections can boast diamond crystals from India, and yet the roots of diamond romance and diamond commerce lie unmistakably there. The world's "first" diamonds were taken from Indian riverbeds as long ago, perhaps, as 800 B.C. (www.diamondcutters.com); a Sanskrit manuscript, the Artha-Sastra, mentions a king of the Maurya dynasty (320-298 B.C.) who regulated an active local diamond trade (Maillard, 1980). Legends associated with the invasion of India by Alexander the Great speak of a "Valley of Diamonds," narrow and deep but laden with gems: men would kill and flay sheep, cast quarters of raw flesh into the chasm, let birds of prey eat the flesh, then kill the birds when they soared out of the chasm, collecting the diamonds which had adhered to the feathers. Variations of this core story spread to China, and later into the Persian and Arab worlds, reaching Europe in 1298, when Marco Polo repeated it in his Book of Marvels. Other early legends claimed that Indian diamonds had the power to neutralize magnetism, and that the most precious diamonds are those which float in water (this one is puzzling, given the high specific gravity of the mineral). Four general grades of Indian diamonds were associated in various ways with the four castes into which classical Hinduism divides humankind. Diamonds could either poison or heal, bring bad luck or good. A myth repeated by Pliny claimed that the diamond's "invincible force" can be "broken" only by applying to the stone the blood of a hegoat: the myth was later allegorized in Christian terms, the diamond being identified with Christ, the he-goat with Satanic powers (Maillard, 1980).

The ancient Romans loved Indian diamonds, and traded for them with native merchants around the "Gulf of Cambay" (today, the Gulf of Khambat, above Mumbai). From the days of the Roman Republic, through the centuries of the Empire, the medieval period, and into the Renaissance,       Photo by jordanrich1
diamonds were brought from India to Europe via two main trade arteries: an overland route, passing through Persia and Byzantium to Rome or Venice, and a southern route, traversing the Indian Ocean and running up through Arabia to Alexandria, and thence to Italy. In the 17th century, the French traveler Jean-Baptiste Tavernier visited some of the Indian diamond mines and brought back much valuable informationincluding legends, already richly textured, about the fabulous Kohi-Noor ("Mountain of Light") diamond. This, the first of the world's major named diamonds, reportedly weighed 600 carats originally, and is now to be seen, facet-cut, in the crown of the English Queen Mother. The great blue "Hope" diamond, now in the Smithsonian, was also found in India, and is likewise couched about with ancient mythic tales, mostly involving the bad luck it brought to its owners.

Most Indian diamonds were harvested from alluvial deposits in the gravels of stream beds, possibly very far from the primary kimberlite pipes. However, some also were probably found in loose eluvium just above a pipe or in colluvial ground adjacent to it. One Greek account of about 120 B.C. speaks tantalizingly of underground diamond mines with deep galleries (Maillard, 1980); these were probably not mines in kimberlite but deep diggings in diamond-bearing conglomerates, called "the pits of Panna" by Williams (1905).

Five areas in India produced diamonds, and one, the largest and richest, became famous under the name "Golconda mines," or "the Kingdom of Golconda," since the town of Golconda was its capital and the center of a large diamond trade (Williams, 1905; Harlow, 1998). all that remains of the opulent "Kingdom" today is a ruined fort near Hyderabad, and the only modern producing diamond mine in India exploits the Majhgawan lamproite pipe near Panna, producing annually about 20,000 carats-0.2% of world output (Levinson et ai, 1992).

During the European Renaissance, Dutch and Portuguese traders competed for Indian diamonds, while at the same time the Portuguese, from their infant colonies on the African coasts, attempted to penetrate the African interior. The Portuguese hoped to find the wealth of "Ophir," the legendary home of the biblical Queen of Sheba and of King Solomon's mines, whence had supposedly come the diamonds (?) on the breastplate of the High Priest of ancient Jerusalem. Nothing came of these early African quests, but Indian diamonds meanwhile poured into Europe along the main internal trade routes running at first from Venice to Antwerp, and then later from Lisbon to Amsterdam. Around 1464 the "Sancy" diamond from India, then owned by Charles the Bold, Duke of Burgundy, was refashioned as a fine facet-cut gem by "the true artist Louis de Berquem of Bruges," in modern Belgium (Williams, 1905), and by the early 16th century a diamond-cutting industry was beginning to flourish in Antwerp. Between the 16th and 18th centuries, first Amsterdam, then London, became the capital of the diamond world. Although Dutch merchants kept investing heavily in the Indian diamond trade, the English by the early 18th century had acquired near-monopoly control of Indian diamonds, and had supplanted the Dutch-by which time, however, the discovery of Brazilian diamonds brought Portugal once more into the game. For a full account of these early-capitalistic maneuvers involving diamonds, and their entwinements with European power politics, see Maillard (1980).

The era of Indian diamonds ended in 1725, when some shiny stones found by Brazilian garimpeiros in an alluvial gold deposit near the town of Tejuco (now Diamantina), in Minas Gerais, proved to be diamonds. The Brazilian era continued until the South African discoveries of the 1860's, and South African diamond production monopolized the field until the first decades of the 20th century. South Africa is still a significant producer, but since about 1920 Zaire (now the Congo Republic), Angola, Botswana, Russia and Australia, in that chronological order, have all surpassed it in annual output. Zaire produces mainly industrial diamonds, and has been doing so since the First World War, when the country was known as the Belgian Congo. Zaire's diamondiferous region lies near the Angolan border, where crystals are found in alluvial gravels and mined from a large kimberlite pipe at Mbuji-Mayi. This country has been so prolific since about 1920 that, surprisingly, it leads the world in total production, as measured by carat weight, for the entire period from antiquity to 1990. Zaire's total all-time figure is 718,117,000 carats, and South Africa, with 446,856,000 carats, comes in second (Levinson et al, 1992).

Kimberlite pipes were first prospected in the Yakutia Craton of northeastern Siberia, Russia, after World War II. There are three major diamond-producing fields here: the adjacent Daldyn and Alakit fields and, about 400 km to the south, the Malaya Botuobiya field. In the summer of 1955, within ten days of each other, the Udachnaya ("success") kimberlite was discovered in Daldyn, and the Mir ("peace") kimberlite was discovered in Malaya-Butuobiya. These occurrences have become fairly well known to mineral collectors, as small numbers of their matrix specimens of diamond crystals in kimberlite have reached western collector markets (Sullivan, 1978; Moore, 1995). The mine at Mir is now idle and flooded, but Udachnaya continues to produce diamonds, as does a very large pipe called jubilileynaya ("Jubilee"). The Yakutia Craton is now the world's second most productive geological province for gem-quality diamonds, after the Kalahari Craton in southern Africa (Harlow, 1998).

Diamonds from the United States have been nothing more than small sideshows on the world scene. The "Crater of Diamonds" at Murfreesboro, Arkansas remains a popular site for tourist diggers in loose "dry ground"; diamonds were first found there in 1906, above what was first called a kimberlite, but is now known to be a lamproitc diatreme (Kidwell, 1990). In the early 1960's, some kimberlite diatremes in Laramie County, Colorado and adjacent parts of Wyoming were found to be diamondiferous (Collins, 1982), and 327 carats' worth of small octahedral crystals were recovered in the early 1990's (Moore, 1997). California also hosts at least one primary deposit, at Leek        Photo by jordanrich1
Springs near Jamestown. Vastly more promising for the future are the diamonds of Canadaa country which bestrides the enormous North American cratonic region, and where, given the vastness of the potential ground, exploration still must be said to be in its early stages. Kimberlite swarms have been located in Saskatchewan and Alberta, but the real excitement during the late 1990's was occasioned by the discovery of diamondiferous diatremes lying around and under Lac de Gras, in the Arctic wilderness of the central Northwest Territories: see Kevin Krajick's recent book Barren Lands (2001) for an exciting account of events leading to the opening of the Ekati diamond mine there, in 1998.

Presently Venezuela, Guyana, Indonesia, Liberia, Ivory Coast, Lesotho and Swaziland all produce some diamonds; and alluvial mining in the northwestern part of Hunan Province, China has recently yielded a beautiful 1.2-cm made twin which appeared in Tucson around ten years ago (Moore, 1993).

THE ORIGIN OF DIAMONDS

Before the latter half of the 19th century, all diamonds were mined from alluvium: the antique crystals from India and Brazil had been found in sediments, loose or lithified, and science had no idea of how the mineral formed in its native rock, or indeed what that rock might be. But the great South African diamond discoveries in the 1860's revealed the rare rock type kimberlite to be the true home of diamonds. The first gem crystals were found loose in the so-called "yellow ground" of weathered kimberlite, and soon the unaltered "blue ground" below was found to contain riches too.

Kimberlite is typically a greenish gray, chowdery-looking igneous rock formed from a magna very rich in volatiles (chiefly CO2 and H2O). The rock is composed of large, irregularly shaped fragments chaotically mixed in a fine-grained groundmass. Whether these "fragments" are phenocrysts crystallized directly from the kimberlite melt or xenolithic inclusions of other rock types was a question which went unresolved for some decades.

Kirkley et al. (1991) define kimberlite as follows:

A hybrid, volatile-rich, potassic, ultramafic igneous rock derived from deep in the earth (>150 km below the surface) which occurs near the surface as small volcanic pipes, dikes and sills [the latter two structures are very rare]. It is composed principally of olivine . . . with lesser amounts of phlogopite, diopside, serpentine, calcite, garnet, ilmenite, spinel, and/or other minerals; diamond is only a rare constituent.

Research eventually established that diamonds come from the included bodies in kimberlite, not from the groundmass; that these bodies are xenoliths, not phenocrysts; and that the xenoliths (and, therefore, the diamonds) are much older than the kimberlite which carried them to the surface.

A deep-seated origin for kimberlite was suspected by early investigators, not only because of its composition, but also because it was found in South Africa as great, carrot-shaped "pipes," the point of the carrot connecting with a system of "feeder" fissures reaching to unknown depths. Of the South African kimberlites exploited by the first mines, some were much more deeply weathered than others, but the general shape of these peculiar structures soon became apparent by comparing what could be seen in the various workings.

Three general zones of a typical kimberlite pipe have been distinguished. (1) The root zone, from the point of the carrot two or three kilometers down and below, generally marks the lower limit of economically profitable mining (even when erosion has brought the root near the surface, the volume of ore is scant). But the pinch-out of the structure is never quite complete; the feeder system is now believed to reach to depths of at least 150 km, i.e. well into the upper mantle. (2) The main body of the pipe widens upwards, and is composed of highly brecciated kimberlite and other rock types. The breccia fragments come from the country
  Photo by jordanrich1      rocks through which the pipe has passed, and from earlier pulses of the kimberlite which hardened before later pulses shattered it during the explosive release of gases. At the top of the pipe, (3) the crater zone originally consisted of a low-relief crater called a maar. This crater area, if it still exists, may be water-filled and may contain substantial amounts of weathered kimberlite "yellow ground." Around the shallow maar craters on the surface there was originally a ring of volcanoclastic debris, called a "tuff ring," about 50 meters high. In most deposits this ring is now gone-it has been observed only in a few places in Tanzania and Botswana-because the deposits are of great age and the clastic debris weathers away very quickly. In fact, kimberlite rock generally weathers quickly: hence the considerable thickness of many yellow-ground beds where the "dry diggings" of South Africa's early diamond rushes took place.
The ascent of kimberlite through overlying rocks is classified broadly as a volcanic event, although kimberlite magma clearly originates at much greater depths than do the more common basaltic and granitic magmas. Because these types of bodies are so different from ordinary volcanic pipes they have been given a different name: diatremes.

Since no kimberlite diatremes have been observed in the process of eruption during man's time on earth (the youngest ones known, in Namibia and Tanzania, date from the Eocene, i.e. at about 55 million years ago), it was a challenge to the imaginations of early investigators to try to picture the eruptive events. With selfconscious vagueness Alpheus Williams (1932) wrote that the kimberlite extrusions "never existed as volcanoes as we understand true volcanoes, but . . . they existed, at all stages, as eruptive fissures." The currently accepted picture is that kimberlite is emplaced as a slurry of brecciated, gas-rich material which, though originally molten at depth, rises explosively through the pipe as a "cold" solid, with multiple pulses of new material shattering already solidified material above. The overall speed of ascent is a fantastic (geologically speaking) 10 to 30 km per hour. At the point in the main body of the diatreme where pressure drops enough to allow the dissolved volatiles to come out of solution, the slurry becomes effectively jet-propelled, rising at velocities of several hundred kilometers per hour during the final few hundred meters (Kirkley et al, 1991). Thus the diamonds transported from where they had rested in "storage" for perhaps 3 billion years at the bases of continental cratons (see later) reach the surface in an ascent that takes only four to fifteen hours (Kirkley et al., 1991). The eruption climaxes in near-surface explosions of expanding gases and spewings of volcanoclastic debris that any observers present would have found extremely dramatic.

That the kimberlite which fills the upper parts of the pipe arrives "cold," rather than as lava, is shown by the fact that there are no indications of thermal effects, such as contact metamorphism, along the walls of the pipe. Furthermore, in some diamond deposits described by Williams (1932), unburned tree trunks and other organic material that collapsed into the crater and became embedded in the kimberlite as it surged up and down have been encountered at considerable depths.

It is interesting to note that diamonds which reach the surface via the kimberlite fast-express are metastable (which is to say that all diamonds we have are metastable): they only remain diamonds, instead of disintegrating or pseudomorphing to graphite, because their rate of ascent was too fast to allow re-equilibration. A small kimberlite pipe at Beni Bouchera, Morocco has yielded fairly sharp, multi-centimeter-sized octahedral "crystals" of graphite paramorphic after diamond: presumably the rate of ascent in this particular pipe was slow enough to allow the crystallographic reorganization to take place (Bob Downs, personal communication, 2002).
A second rock type, lamproite, which likewise erupts from great depths to form pipes, can also be diamondiferous. Lamproite is less gas-rich than kimberlite and its eruptions are less violent; the near-surface configurations of lamproite pipes tend to be wider (champagne-glass-shaped) than those of kimberlite (Harlow, 1998). Lamproite is also somewhat different mineralogically (see the later discussion of the Argyle mine in Australia), although the diamonds in the two rock types do not seem to differ in any important way. Lamproites, like kimberlites, occur in the continental cratons, or on their margins, and, also like kimberlites, range very widely in age: the Argyle lamproite pipe is about 1,200 million years old, but the Ellendale lamproite pipe, only 400 km from the Argyle, was intruded in the Miocene, only 20 million years ago (Kirkley et al., 1991).
                                                                                                                                           Photo by jordanrich1  
But where and how do the diamonds originate? This was the mystery which a great number of theorists began trying to solve as soon as the South African kimberlite pipes were discovered. When, in 1905, De Beers general manager Gardner F. Williams published the two volumes of The Diamond Mines of South Africa, little headway had yet been made on the question of how and where diamonds form, but by 1932, when his son, Alpheus F. Williams, published his own two-volume work, The Genesis of the Diamond, three broad classes of theories had evolved. Some geologists argued that the diamonds crystallized in situ out of kimberlite magma during the time when the (presumed) magma was solidifying in the pipe. Other geologists also thought that diamonds crystallized out of kimberlite, but argued that they did so at depth, before the ascent of the pipe. A third school held that the diamonds formed at depth in ultramafic rocks other than kimberlite, and were later caught up in the kimberlite melt, as constituents of xenoliths (Williams, 1932). The first of these theories was a casualty of the realization that near-surface kimberlite is emplaced as a cold solid, not as a magma. The other two theories remained for several more decades in active contention, being called informally the "phenocryst school" and the "xenolith school" (Kirkley et al., 1991). Alpheus Williams himself adhered to the phenocryst school, presenting at great, careful length in his book the argument that the large included fragments in kimberlite are of essentially the same composition as the fine-grained groundmass, i.e. that the fragments are cognate, not xenolithic. However, the debate is now settled: the fragments are indeed xenoliths, and diamond crystals are not products of the kimberlite but, as components of xenoliths, are mere passengers on the kimberlite fast-express to the surface. This triumph of the xenolith school is a product of two basic lines of mid to late 20th-century         Photo by jordanrich1
research: (1) petrological study of the xenoliths themselves, as correlated with evolving knowledge of the earth's mantle and of plate-tectonic processes, and (2) modern analytical studies utilizing sophisticated instruments for the investigation of the mineral components of the inclusions in diamonds, and of the ages of these inclusions.

The xenoliths found in kimberlite (and lamproite) are of two rock types, both known to be common in the upper mantle around and under the continental plates: eclogite, and a more broadly defined type generally called peridotite. Eclogite is a coarse-grained, attractively colored red-and-green rock consisting of about 50% garnet (almandine-pyrope) and 50% clinopyroxene, with minor rutile, kyanite, corundum and coesite; it is thought to result from profound metamorphism of subducted basalt under tectonically active margins of continental plates (basalt and eclogite are identical in their bulk chemistry-Kirkley et al., 1991). By contrast, the xenoliths classed as "peridotite" average about 50% olivine (forsterite), 40% pyroxene, and 10% garnet. Diamonds are known to occur in three peridotite subtypes: dunite (90% olivine), harzburgite (40-90% olivine, the rest orthopyroxene and garnet), and Iherzolite (at least 40% olivine, with orthopyroxene and clinopyroxene in a wide range of proportions, and minor garnet). Peridotite of these varying types, as found just beneath the crust in the stable interior zones of continents (cratons), probably is primordial upper-mantle material, having remained little changed since the first differentiation of crust from mantle in the very early earth (see later).

Diamonds which have been brought to the surface in eclogite or peridotite xenoliths have come to be called respectively "E-type" and "P-type" diamonds. Either may be found still embedded within the host xenoliths or floating in the kimberlite groundmass after the fragmentation of xenoliths during the violent events of ascent. Eclogite, being the tougher of the two rock types, is found much more commonly as intact xenoliths in kimberlite at the surface. Eclogite xenoliths are commonly fresh-looking, whereas the much rarer peridotite xenoliths are usually crumbly and/or altered around their rims. Studies of inclusions in diamonds have shown that P-type diamonds are much more common than E-type diamonds, even though the greater survival rate of eclogite matrix fragments would seem to suggest the reverse. This is one illustration of how the study of the xenoliths alone can be misleading unless supplemented by diamond-inclusion studies.

Research on inclusions in diamonds began to yield hard results in the 1970's, with the attainment of required levels of sophistication in X-ray diffraction techniques, electron and ion microprobe analyses, and the dating of trace isotopes (Meyer, 1985; Kirkley et al., 1991). These minute inclusions (mostly around 1 µm, or 0.001 mm), having been shielded from later changes by the enclosing diamond, represent our best and most pristine samples of mineral suites from upper mantle rocks. Although most diamonds show inclusions of only one mineral species, polymineralic inclusions are (fortunately) also found. Thus far, 22 mineral species (including diamond itself) have been identified as inclusions in diamonds, and although   Photo by jordanrich1
six of these may be found either in eclogite or peridotite, detailed analyses have revealed two mutually exclusive assemblages of included minerals, making it possible to assign 98% of all included diamonds to either the E (eclogite) or the P (peridotite) categories (Meyer, 1985).

It has also been possible to draw some inferences about the temperature and pressure conditions, and therefore the depths of diamond formation, in these two rock types. Correlating with these results are the isotopic age-dating studies of the tiny inclusions, which have led to the approximate dating of the formation of the host rocks, and therefore the ages of their diamonds (it is not yet possible to age-date diamonds directly).

Both of these lines of research indicate that upper-mantle eclogites and peridotites formed at different times and by different processes in the deep earth, and that kimberlite melts at depth may have taken up diamond-bearing xenoliths from either environment (or from both), for transport to the surface. It remains to consider the nature of these two environments, and to summarize current thinking which seeks to correlate the distribution of diamondiferous diatremes with plate-tectonic processes.

Geothermal and geobarometric studies of e-type diamonds have shown that these diamonds have a higher temperature of crystallization, and form at greater depths, than P-type diamonds (Meyer, 1985; Kirkley et al, 1991). Eclogite, as already mentioned, is characteristic of very deep parts of subduction zones, well within the upper mantle below continental platforms, where the subducted basalt of the former sea floor metaphorphoses to eclogite. P-type diamonds, on the other hand, are believed to form in peridotites of the shallower upper mantle; they come from depths in the range of 150-200 km below the surface, whereas E-type diamonds from one South African mine, for example, have been assigned depths of formation of more than 300 km. Radiometrie dating of trace isotopes of Rb-Sr, Sm-Nd, and U-Pb in the inclusions has revealed that all of the diamonds occurring in the peridotite xenoliths are around 3 billion years old. This theme of immense age was also sounded quite early in the modern history of diamond studies, for it was realized early that most of the earth's swarms of kimberlitepipe intrusions occur in stable continental cratons of Archaean age.

The now-favored model of the genesis of P-type diamonds involves the insight that "in Archaean times there was a unique process accompanying crustal formation: a combination of melt extraction, fluid interaction, and diamond crystallization that sometimes left a relatively cool, rigid, deep keel beneath a continental plate" (Harlow, 1998). From the plausible hypothesis that these isothermally defined "keels" below the cratons have remained constant through all geologic time since the Archaean, it is inferred that P-type diamonds were formed no later than about 3 billion years ago, and at depths of 150-200 kilometers.

The question of the source(s) of the carbon in diamond has also been considered. In carbon-isotope studies of diamonds, the term O13C denotes the ratio of the carbon isotopes C12 and C11; these studies have found stark differences between the carbon in P-type and E-type diamonds. In the former, there is a very tight clustering of [delta]^sup 13^C values within a narrow range, whereas in the latter there is a much wider [delta]^sup 13^C distribution across a broad range. This is to say that the carbon in P-type diamonds had a uniform and stable source in the upper mantle: it is thought to be "primitive" carbon which accumulated in a stable convective zone perhaps 4.5 billion years ago, at the time when the first continental cratons were forming. (One intriguing modern theory suggests also that some of this "primitive" carbon may have come from convection cells transporting liquid metallic C to the upper mantle from the lower mantle-Meyer, 1985.)

By contrast, the carbon in eclogitic (E-type) diamonds is thought to have been transported to deep levels with the basalt of the subducted sea-floor plates, such that when the basalt turned to eclogite, the carbon turned to diamonds. In this case, the sources of carbon might have included both carbonaceous crustal sediments (e.g. limestones from geosynclinal trenches) and organic remains on the ancient seafloors. The differences between the carbon of P-type and E-type diamonds correlate well with the derived ages of diamonds of the two types. all P-type diamonds have been found to be very old, at least 3 billion years, whereas some E-type crystals are well under 1 billion years old-suggesting that E-type diamonds may be the byproducts of different tectonic cycles of differing ages. (These age-dates for the diamonds themselves are not to be confused, of course, with the dates of intrusion of the kimberlite pipes, which range, for known pipes, between 1,600 and 50 million years ago).

Since the discovery of the first African kimberlites, the worldwide hunt for more such structures has revealed a definite pattern of distribution: kimberlite and lamproite diatremes are almost always found within the innermost, stable parts of continental shields-the original and most ancient, cratonic nuclei of continents. The diagram shown here illustrates the most favored current theory explaining how these cratonic diatremes can contain both ?-type and P-type diamonds. P-type diamonds repose in the cooler thermal "keel" of very old upper-mantle peridotite under the craton, wherein they formed during very early times. E-type diamonds occur in the eclogite below this keel, which has been subducted (originally as sea-floor basalt), perhaps at a much later time. A kimberlite diatreme such as Kl on the diagram, having passed through both regions, will contain diamonds of both types, with those of the P-type probably predominating. A diatreme such as K2 will have "sampled" only the eclogite region and thus will contain only E-type diamonds. A diatreme, like K3, situated out too far from the cratonic center, will have "sampled" neither region and thus will be barren of diamonds. Ll represents a lamproite diatreme of the Argyle, Australia type, situated near a cratonic margin and containing both E-type and P-type diamonds, perhaps because of a complex system of interconnecting fractures at depth (Kirkley et al.., 1991).

Although the general picture sketched above would seem to account very well for the great bulk of the world's diamonds, one anomalous occurrence in New South Wales, Australia has recently given rise to an alternate model of diamond formation which may sometimes apply. About two million diamond crystals, with an aggregate weight of about 500,000 carats, have been found in alluvium in the Copeton-Bingara area, in eastern New South Wales. Despite intensive exploration, no kimberlite or lamproite diatremes have been found in the area, and the nearest cratonic block (west of Broken Hill) is about 1,000 km away. If a nearby source for the diamonds is posited, another theory of their formation and/or transport to the surface is needed, and such a theory was published in 1996 by Barron et al. Very briefly, these authors propose that the diamonds were formed in subducted oceanic plates along the eastern margins of Australia, at only about half the depth thought typical for diamond formation in the subducted eclogites of the "standard" model outlined above. When this oceanic crust plunged under the continental plate, the authors argue, it remained much cooler than its surroundings; the combination of rapidly increasing pressure and relatively low temperature opened a "window" into the stability field of diamond. Subduction then stopped, preserving the diamonds which had formed, and later these were transported to the surface by non-kimberlitic magmas such as leucitite, melilitite, nephelinite, and basanite-"diamonds have been found in several diatremes and dikes with these compositions in eastern Australia" (Barron et al, 1996). The authors correlate various characteristics of the Copeton diamonds-nitrogen content, color, carbon isotopic composition and others-with several rock types that presumably existed in the original oceanic plates, and they propose that, depending on the rock type, the carbon was either of "primitive" origin or existed as limestone or organic remains in trench sediments. Some diamond formation, they suggest, may even have been catalyzed by natural fullerene carbon molecules. Once formed, the diamonds rested in "cold storage" in their static, partially subducted rock slabs, whose temperatures remained low, for up to 100 million years before transport to the surface.

Obviously, the whole question of diamond formation is still dynamically open, and there are many remaining uncertainties even in the "standard" picture. What, for example, is the detailed nature of the processes which accumulate carbon in the primordial peridotites? How much of the carbon in E-type diamonds is organic in origin, and how young might the E-types conceivably be? Why do kimberlite melts form at depth, and what propels them so rapidly to the surface? The sense of romance that clings like an aura around diamonds arises not only from their beauty, their gemstone value, and their rich historical lore, but also from the unsolved mysteries which still persist in the shadowy, remote reaches of deep-earth science.
 

Localities of Diamonds

Estralla do Sol, Mato Grosso Province, Brazil

According to one story, Brazilian diamonds were first noticed by a Portuguese, Sebastino Lerne do Prado, when he saw gold prospectors using them as chips in card games, around 1725 (Maillard, 1980). Another version of the story, recounted by Williams (1905), says that it was black slaves who conducted the card games. From 1728, when the Portuguese government learned of the stones, until the blossoming of South Africa around 1870, Brazil reigned supreme in the world for diamonds. Cassedanne (1989) estimates that 13 million carats, or 2 metric tons, of diamonds were produced from Brazilian fields over roughly a century. During the 1730's, just after the first discoveries, Europe's supply of diamonds quadrupled, and diamond prices plummeted, partly because of the mistaken feeling that the new source of supply would prove inexhaustible. all Brazilian diamonds were declared to be the property of the Portuguese state, and all diamond mining declared to be a Crown monopoly. This simple policy, based on simple state greed, ensured that the industry would remain static, without achieving major advances in mining techniques or in economic development of the diamond market (Williams, 1905).

Mid-20th-century prospecting revealed hundreds of kimberlite outcrops in Brazil, but all mining during the period 1725-1865 took place in alluvial, eluvial or colluvial deposits. Some lithified "bedrock alluvial" sites were worked by benched quarries, and matrix specimens of diamond crystals in coarse conglomerate were sometimes found. Miners to this day may try to sell visitors fake specimens of this type, with the crystals glued onto the matrix (Cassedanne, 1989).

In the early days, mining was done by slaves under the whips of the Portuguese. After Brazilian independence there was much freelance prospecting, and garimpeims often formed co-operative organizations, the miners sharing the work and dividing the profits among themselves and with financial backers, as well as with owners (if any) of the lands hosting successful prospects.

Diamond fields speckle most of the southern half of the country, but the richest sites, and the earliest found, stretch along the Jequitinhonha River for many tens of kilometers north of the town of Tejuco (Diamantina). Diamonds there are found in gupiaras (coluvial terraces high above the streambeds), gorgulho (eluvial plateau deposits), and cascalho (gravel deposits in the streams). In the cascalho deposits, the most important type, gravels were (and are) washed and sorted in complex systems of hoses, pumps, sluices, and washing crates, while women and children comb adjacent parts of the drainages for diamonds. A mechanized dredging operation in the Jequitinhonha River, 80 km downstream from Diamantina, is the only contemporary Brazilian diamond "mine," producing 1 carat of diamond and 1 gram of gold for each 100 cubic meters of gravel (Maillard, 1980; Cassedanne, f989).
The featured collection's only Brazilian diamond is a typically frosty and somewhat irregular crystal measuring 1.3 cm and weighing a little over 11 carats. It comes not from Diamantina, Minas Gerais, but from "Estralla do Sol, Mato Grosso." The province of Mato Grosso is in west-central Brazil, bordering Goias Province on the east and Bolivia and Paraguay on the west; its capital is the town of Diamantino, near which the chief diamond field of the province is located. Prospecting for diamonds (and gold) in this remote region has never been as intense as in the other fields to the east. According to Cassedanne (1989), "A period of excitement and wealth was short-lived, ending in 1847 with the decline in gold production. In the year of 1852 the Mato Grosso Mining Society went bankrupt [and] the Diamantino prospect was abandoned."

In recent years, however, diamond mining activity has picked up in the province. Near Diamantino and north of the city of Cuiaba, a 63,000-hectare claim block now known as the Mato Grosso Diamond Project was host to a large-scale diamond rush in the 1960's, when alluvial diamonds were first discovered in the Morro Vermelho Formation. The proliferation of high-quality diamonds being found by prospectors in the area attracted several major diamond mining companies, and more than 50 kimberlite pipes were discovered. Diamonds collected from the property exhibit pristine or near-pristine surfaces, suggesting a local source for the significant number of alluvial diamonds found on the claims. Eclogitic garnets have also been found in two of the initial heavy mineral samples collected. Iciena Ventures, Inc. is part owner in the project, and recently announced the acquisition of 47 prime diamond exploration permits covering 438,000 hectares in the states of Mato Grosso and Rondonia, Brazil (www.iciena.com).

An area in the southern tip of the state of Rondonia and the northwestern part of the state of Mato Grosso also has large reserves of diamonds. Mining is forbidden there because it is in the protected homeland of the Cinta Larga Indigenous People; however, nearly 3000 garimpieros and miners entered the area illegally to mine diamonds in 1999, and eventually had to be evicted by government troops. The Federal Police estimates that gems amounting to 50 million dollars were smuggled from the region to Belgium last year.

In the juina Diamond Province, Mato Grosso, the Diagem International Resources Corporation currently has 130,000 hectares of mineral claims. The Province has vast deposits of alluvial diamonds as well as 7 identified diamondiferous kimberlite pipes on which basic exploration is complete. Over 130,000 carats of diamonds were recovered during the evaluation phase, including large stones up to 450 carats, and a 100-carat pink crystal. Production began in 1996 (www.diagem.com). Author Moore, Thomas


Argyle mine, Western Australia, Australia

No diamonds from Australia reached the world market until 1981, but by 1995 the country had assumed first place in annual diamond production worldwide. Most of this ballooning output has come from the Argyle mine, in the East Kimberley diamond province, situated in the northeastern part of Western Australia. The workings consist of a huge open-pit mine in a lamproite pipe. It is somehow satisfying, though merely coincidental, that this Australian "Kimberley" region was named (in 1880) after the same Earl of Kimberley, then British secretary of State for the Colonies, after whom the great De Beers New Rush diamond mine in South Africa had been renamed the Kimberley mine in 1873 (Grice and Boxer, 1990).

What have Victoria Beckham, Jennifer Lopez and other celebrity in common ? . They own some diamonds from the Argyle-Mine in Australia. Pink diamonds from the Argyle-Mine fetch around 10 times the price like a "ordinary" white diamond of similar quality and size. The diamond right above costs as much as a nice fully equiped Rolls Royce. The Argyle-Mine in Australia is operated by  Rio Tinto Diamonds. This diamonds of a very rare and beautiful red color are almost only to be found in der Argyle-Mine. It looks like somewhere around 2018 the mine will dry up, that means this kind of diamonds have a bright future in terms of prices.

Australian diamonds were first found in New South Wales in 1851, in alluvium being washed for gold, and New South Wales produced modest quantities of diamonds for a few decades thereafter. In Western Australia, although a few alluvial diamonds were found near Nullagine in 1895, major prospecting did not begin until the late 1960's. A few kimberlites and a few diamond-bearing alluvial deposits were found in the Ellendale and Noonkanbah areas in the early 1970's, but the real bonanza followed the discovery, in 1979, that Smoke Creek was full of diamonds. Prospectors following an easy trail of these alluvial deposits upstream for about 20 km came to the primary source-the Argyle (AKl) lamproite pipe.

This was only the second (Murfreesboro was the first) primary diamond deposit found anywhere in any rock other than kimberlite-and there are now known to be at least 100 other lamproites in the Kimberley area, many of which contain diamonds (Harlow, 1998). Though similar in its origins to kimberlite, lamproite is finer-grained and lighter-colored (typically it is gray to greenish gray, and mottled), and differs somewhat in its mineralogy. The major component species are forsterite, phlogopite, diopside, richterite, chromite and pyrite, and some of the lamproites of the Kimberley area also contain some very rare species, including priderite, jeppeite and wadeite (Grice and Boxer, 1990). However, diamonds from lamproites do not seem to differ in any important way from those found in kimberlites. Argyle mine diamonds show a wide range of crystal forms, colors and twinning habits, but such a range is also commonly seen in kimberlite diamonds.

Argyle mine crystals average only 0.1 carat in weight. The largest found up to 1998 weighs 41.7 carats. Only about 5% of the crystals are of gem quality. In 1995 the mine produced 38% of the world's diamonds as measured by weight, but just 6% as measured by value (Harlow, 1998). About 75% of the stones have dark inclusions, rendering them brown, yellow, or (in cases of larger, "bort" diamonds) steel-gray. However, a few rare stones are green or colorless, and pale pink ones are something of a specialty of the mine, making lovely and very valuable gems (see a dramatic photograph of a swarm of pink crystals in Grice and Boxer, 1990). The Argyle diamond crystals in the collection featured here are a lovely, gemmy brown, 1.1-cm octahedron weighing about 4.4 carats, and a smaller but sharper, purplish brown octahedron measuring 6 mm.

Production at the Argyle mine began to fall off in 1999, and the deposit is expected to be largely exhausted, and the mine to close, by 2006. However, Ashton Mining, the company which operates the mine, should recoup any loss of income, as it is also 100% owner of Australia's only other hard-rock diamond operation, at Merlin in the Northern Territory. This mine, which began production in 2000, exploits a number of small kimberlite pipes with much higher gem-quality diamond content than Argyle's, and it is expected to remain productive for a long time to come (www .mbendi.co.za).
Orapa mine and Letlhakane mine, Botswana

Between 1967 and 1973, DeBeers geologists located three richly diamondiferous kimberlite pipes in Botswana (formerly British Bechuanaland), with the eventual result that this poor, underpopulated nation in the Kalahari Desert (and right over the center of the Kalahari Craton) is now third in the world in diamond production as measured by carat weight, behind only Zaire and Australia. Moreover, since there is a very high ratio of gem-quality to industrial quality diamonds here, Botswana since the early 1990's has led the world in diamond production as measured by value. Many kimberlites occur in the country besides the main three (Orapa, Letlhakane, Jwaneng), and many smaller mines are now working. Nearly all diamond production is controlled by the Debswana Diamond Company, a joint venture firm of which 50% is owned by De Beers and 50% by the government of Botswana (www. mbendi. co. za).

The Orapa kimberlite pipe, discovered in 1967, is exploited by the second largest pipe mine in the world, surpassed in size only by the Williamson mine in Tanzania (Webster, 1983). The outcrop of the Orapa pipe-the only known kimberlite pipe in Botswana not overlain by sand-covers 263 acres; production commenced in 1970 (Harlow, 1998) or 1971 (Webster, 1983). The Orapa kimberlite is remarkably well preserved, having suffered less erosion than any other known major kimberlite pipe. Only the topmost few meters are missing, and the great bulk of the diatreme remains intact and awaiting exploitation (Kirkley et al., 1991). As of 2000, after a major expansion of the open-pit mine, the Debswana Diamond Company planned to shift to an underground operation, working through twin vertical shafts to reach the lower sections of the kimberlite. The life expectancy of the mine has been estimated at another 30 years (www.mbendi.co.za).

Illustrated here is a truly extraordinary suite of 21 Orapa mine diamonds, most of them in various shades of yellow, but also including two large multiple-crystal clusters to 2.2 cm and two lovely, gemmy pink crystals to 5 mm (one of them a tetrahexahedron). Several of the yellow crystals show cubic penetration twins, and two have an odd skeletal habit that is probably the result of twinning.

Near the town of Letlhakane, 48 km northwest of the Orapa pipe, two smaller pipes, Letlhakane 1 and Letlhakane 2, were discovered in 1968. The mines here came into production in 1976; nearly 40% of the diamonds found in them are of gem quality (Webster, 1983). The specimen shown here is a very gemmy, faintly yellow, 1.6-cm crystal weighing about 12.6 carats.

The third and greatest of the diamondiferous kimberlite pipes in Botswana (not represented in the collection featured here) is the Jwaneng, much farther south than the Orapa and Letlhakane. This is the second most productive single diamond mine in the world, after the Argyle mine in Australia, in terms of carat-weight, and the world's most productive in terms of value (since, again, the percentage of gem crystals is very high). The pipe is hidden under 165 feet of sand; its discovery in 1973 was the result of a rigorous search program directed by Dr. Gavin Lamont of De Beers (Maillard, 1980).

Kimberley district, Cape Province, Republic of South Africa

"Kimberley district" is unfortunately a vague term for the purposes of a label, since several kimberlite pipes near the town of Kimberley have produced diamonds in huge numbers-not to speak of the comparably huge numbers of alluvial diamonds found in the area before (and since) their primary sources became known. This is certainly the most famous of all the world's diamond regions, whose history has been written in many places. Offered here are only a few points of "color"; for a really full story told by an upclose observer/participant, see Gardner F. Williams' The Diamond Mines of South Africa (1905).

The history begins in late 1866 or early 1867, when some children of a Boer (Dutch-descended) farming family named Jacobs found a transparent, 21-carat diamond on the south bank of the Orange River-some say that the finder specifically was 15year-old Erasmus Jacobs, others favor a daughter named Fredrika, and other candidates for the honor also exist (Janse, 1995). Mrs. Jacobs showed the pretty stone to a neighbor named Schalk van Niekerk, telling him that if he liked it he could keep it; she was accustomed to seeing piles of such pretty stones (only smaller) that the children built in the fields. After several more casual changes of hands the plaything ended up with Lorenzo Boyes, who was either acting Civil Commissioner of the British Cape Colony (Williams, 1905) or the town clerk of Colesberg (Janse, 1995), and Boyes, having the stone tested, found that his suspicion had been correct: it was a diamond. Frenzied rushes of diggers to the gravel beds of the Orange and nearby Vaal Rivers followed (see later), and then came the rushes to nearby "dry digging" sites, where diamonds were being picked from loose deposits of yellow, calcareous dry mud on farmers' lands.

At first, and despite the dryness and heat of the work sites, this mud-"yellow ground"-in which the diamonds occurred was thought to be some kind of water-deposited sediment; after all, the searchers had just recently been finding alluvial diamonds in riverbeds. When, at some sites, they neared the bottom of the dry, yellow mud, revealing a hard bluish-gray rock beneath, some diggers gave up and sold their claims, believing that the diamondiferous ore had run out. But those optimists who kept working, hacking into the "blue ground," were delighted to find that diamonds continued to appear. Noting how easily the mysterious rock weathered, they broke it up and spread it out in the sun in wide "floors," so that after six months or so it would turn, in effect, to yellow ground which could be sieved to recover the diamonds (Janse, 1995). In 1872 the German mineralogist Emil Cohen became the first to propose that the dark cylindrical columns of rock, as uncovered below the weathered zone, were in fact volcanic pipes. During the rest of the decade the idea that diamonds come from these igneous pipes won general assent, and in 1887 the American mineralogist Henry Carvill Lewis proposed the name kimberlite for the rock.
By this time the great diamond mines in the blue ground had already been initiated in quick succession. Four of the deposits fall within a circle 5 km in diameter, which includes also the city of Kimberley. In order of their discovery they are Bultfontein (September 1869), Dutoitspan (October 1869), De Beers Old Rush, later simply De Beers (May 1871), and De Beers New Rush, later Kimberley (July 1871). Two more pipes, Koffiefontein and Jagersfontein, lie 90 and 150 km respectively to the southeast. In 1890 another huge pipe, Wesselton, was found only 3 km from Bultfontein and Dutoitspan.

The De Beers mine was begun on a farm, called Vooruitzigt, owned by two Boers, the De Beers brothers. They sold the land for a sum that anyone more sophisticated would have thought negligible, then couldn't think what to do with the windfall except perhaps buy a new wagon and some ox yokes (Krajick, 2001). But, because the mine named after them ultimately became so famous, their name eventually became attached to the great diamond cartel called De Beers, still one of the wealthiest and most powerful business concerns in the world.

As already mentioned, the first Kimberley diamonds were found in the loose yellow earth of shallow "pans," as dry ponds were called by the Boers-"Dutoitspan" literally is the "pan" on the land of a farmer named Du Toit. The news of these thrilling new kinds of diamond fields reached the alluvial diamond-digging communities on the Orange and Vaal rivers very quickly, of course; and soon the taciturn, pious Boers who owned and farmed the lands found themselves overwhelmed by fame, although, for the most part, not by any instant wealth. Makeshift leasing and royalty arrangements were insufficient to cope with the numbers of people and volumes of potential profit involved, and the Boer government of the new, tiny, precarious Orange Free State was out of its depth. It tried to restrict the allotment of claims on the farm lands to all but citizens of the Free State, but since the claimants in reality came from every part of the world and every moral terrain of the soul, the Free State government soon lapsed into passivity.

Besides, the regional politics were complicated and tricky. Some indigenous tribes still asserted a vague kind of claim to some of the diamondiferous lands. The Orange Free State, of course, also asserted a claim; and in Capetown there was the increasingly aggressive authority of the British Cape Colony under its new High Commissioner, Sir Henry Barkly. In 1871 Sir Henry concluded an arrangement, subject to (routine) ratification by Her Majesty's government, for the transfer to Great Britain of the claims of the native African chiefs. After some legal maneuvers which had the effect of locking out all claims of the Orange Free State, British sovereignty over the new Crown Colony of Griqualand West, which included the diamond fields, was proclaimed. The imperial gesture probably helped ensure that the diamond fields would be exploited with maximum profitability, and was in any case surely in tune with the times. A voice clearly speaking from the mind-set of those times (that of G. Williams, 1905) rhapsodizes that ". . . this settlement was greatly contributory to the extraordinary advance of diamond mining ... as well as to the uplifting and development of the Colonies, and to the push of civilization into the heart of the dark continent."
No one better personifies this Imperial spirit than Cecil John Rhodes, who, in the rhetoric of Williams (1905) again, sought "to reach ends of Imperial scope, to throw the searchlights of civilization into every cranny of the Dark Continent, to lift the prodigious dead weight of unnumbered bygone ages of barbarism ... to create a Greater Britain ... and stretch the hand of his Queen over a realm transcending the farthest sweep of the Macedonian or the Roman." By the time of his death in 1902, Rhodes indeed had done more than anyone else to make southern Africa British, as far north as Kenya and Uganda-working from a power base secured by diamonds and by his mighty creation, the De Beers corporation.

When Rhodes came to Africa in 1870 to seek diamonds, he was merely the sickly 17-year-old son of a Hertfordshire clergyman. It was his ambition, imagination, and financial daring which finally gave him the victory, after years of capitalistic battle, over another ambitious adventurer, a Jewish shopkeeper from London named Barnett Isaacs, also known as "Barney Barnato." Barnato had come to work as a "kopje wallower" (amateur diamond buyer) in the Great White Camps of the diamond fields in 1873, joining his older brother Henry. With an equally inexperienced partner, Louis Cohen, Barnato soon began buying up claims, and founded a diamond company-thus moving into direct competition with Rhodes, who was doing the same sort of thing. The two entrepeneurs' rivalry did not end until 1887, when Rhodes bought out Barnato and incorporated their combined holdings as the De Beers Consolidated Mines Limited. Rhodes' other great creation, the British African Empire, is now gone, but the De Beers cartel is supreme to this day in the (now worldwide) diamond trade.

One dramatic episode in the early history of Kimberley deserves mention. In 1899 the Boer War broke out, itself a perfect artifact of British imperialism, as the British victory ended all Boer, not to speak of native African, aspirations to independence. Between October 1899 and February 1900 the Kimberley mine, and Kimberley town, came under military siege. An ill-organized but well-armed force of angry Boers surrounded the town/mine complex and bombarded it with long-range artillery; fortifications around the town and mine were erected, and small engagements were fought between British patrols and the besieging forces. In advance of the siege Rhodes had sent from Capetown a small but stout British force and ample supplies; food was rationed during the siege, and some diamond mining even continued. During one period of especially fierce bombardment, several hundred women and children took refuge for several days in the mine's deep tunnels. By the time a British relief column finally arrived, nine people had been killed in Kimberley, and many houses destroyed, but the brave defense had solidified local pride, and no permanent damage had been done to the mine.

In 1914 the Kimberley mine closed, having been worked to a depth of 1,098 meters; its site is presently marked by the famous "Big Hole," the deepest manmade excavation on earth. Four of the giant original mines are still active today: Bultfontein, Dutoitspan, Wesselton and Koffiefontein. Their combined production during the 1990's averaged only about 700,000 carats of diamonds annually, accounting for 0.7% of world production. The mines are close to the bottoms of their reserves of kimberlite ore, and all may be closed permanently by 2010 (Harlow, 1998).
The Kimberley diamond crystal illustrated here is a very gemmy, interestingly modified 1.4-cm octahedron weighing 11.3 carats.


Premier mine, Transvaal, Republic of South Africa

Up until 1903 the mines around Kimberley had supplied all of South Africa's (and the world's) kimberlite diamonds. But in that year a large diamondiferous pipe 20 miles from Pretoria, in the province of Transvaal, went into production as the Premier mine. Diamonds had been found abundantly in the soil there, especially around the Elandsfontein farm, as far back as 1897, but apparently some South Africans were reluctant to think that this new kimberlite deposit could possibly rival the already world-famous mines at Kimberley, almost 500 km to the southwest. In an official report in june, 1903-after the "Cullinan" diamond had been found in the Premier mine-a mining engineer employed by the Transvaal government noted that although the soil of this region was indeed full of diamonds, the blue ground below would probably prove unprofitable; others in the Transvaal Bureau of Mines shared this view (Williams, 1932).

But according to a report issued on October 31, 1903 by the Premier Diamond Mining Company, the Premier mine had already produced almost 100,000 carats of diamonds, valued at £137,435, during the first few months of its start-up year. Ten years later the company reported that the Premier mine had yielded 2,107,983 carats of diamonds worth £2,336,828 in the year ending October 31, 1913 (Williams, 1932).

The mine achieved its highest average annual production of diamonds during the 11-year period between its opening and the temporary suspension of mining at the outbreak of World War I in 1914. Work resumed in 1917, and by 1932, when the open pit had reached a depth of 610 feet, there was still almost no decrease in the diameter of the kimberlite pipe (Williams, 1932). But soon thereafter the miners encountered a sill of gabhro intersecting the pipe (Bancroft, 1984), and because of this barren ground the old open-pit Premier mine closed in 1936. In 1946 it re-opened, this time as an underground mine exploiting kimberlite below the gabbro, and as of today, one year past the mine's centennial, diamond production still continues. The deposit enjoys record longevity in another sense too: it is geologically the oldest of the major known kimberlite intrusions, dating between 1,100 and 1,200 million years (Bancroft, 1984; Kirkley et al., 1991).

On the popular level, the story of the Premier mine is the story of Thomas Cullinan, and of the "Cullinan" diamond. Thomas Cullinan, born in the British Cape Colony, inherited a prosperous construction business, but before the turn of the 20th century he sold off most of his assets and moved north, into the Witwatersrand area near Johannesburg, Transvaal, where he devoted himself to prospecting for diamonds. Knowing that they occurred in the soil near the farm called Elandsfontein, he offered to buy the farm from its owner, Joachim Prinsloo, who responded by threatening to shoot Cullinan and any other prospectors who might trespass on his land. The Boer War put a halt to most prospecting anyway, and Prinsloo died before the war ended. In November 1902, the persistent Cullinan was finally able to purchase the farm from the Prinsloo heirs for £52,000.
In January 1903, diamondiferous kimberlite began to show up in the prospect pits, and a De Beers geologist came for a look. Apparently sharing the general skepticism about the viability of any kimberlites outside of Kimberley, he reported to his superiors that this new mine would be "a flash in the pan" (Janse, 1995). On Janauary 25, a gigantic diamond was found less than a meter below the surface, and mine manager Frederick Wells dug it out of the ground with his penknife (Bancroft, 1984). It was, of course, the fist-sized, 3,106-carat "Cullinan" diamond, by far the largest gemquality diamond ever found anywhere in the world. Bancroft (1984) tantalizingly points out that the overall shape of the "Cullinan" indicates that it was actually the smaller half of an enormous, cleaved octahedron, and somewhere the still-buried larger half of the same crystal must certainly still exist.

The Cullinan diamond was presented to King Edward VII, and of the 105 separate gemstones cut from it, the largest two, the Great Star of Africa and the Lesser Star of Africa, at 530.2 and 317.4 carats respectively, are the largest faceted diamond gems in the world. Today they are seen by the thousands of tourists who visit the display of the British Crown Jewels in the Tower of London each week.

As the production figures cited earlier show, the Premier mine during its amazing first years provided strong competition for the mines of the De Beers monopoly at Kimberley. De Beers, moving quickly to rectify its earlier error in judgment, reached an "understanding" with the board of directors of Thomas Cullinan's Premier Diamond Mining Company in 1920, and by 1922 De Beers had acquired all shares in the Premier mine (Janse, 1995). Cullinan was knighted by Edward VII, and went on to a successful career as a South African politician; he died in Johannesburg in 1936.

The four Premier mine crystals illustrated here include a gemmy, modified, 9-mm octahedron, an interesting pair of gemmy and colorless octahedral crystals attached to each other in parallel, a 1.3-cm octahedron darkened by many blackish inclusions, and an extraordinary 1.3-cm crystal cluster consisting of at least seven gemmy, octahedral individuals growing on a matrix lump of opaque diamond "bort."

Vaal River district, Cape Province, Republic of South Africa

The Vaal River, rich in alluvial diamonds, passes through the "Kimberley district" of kimberlite-pipe mines (see above); in fact, a bend of the river passes within two km of the Kimberley mine. This description, therefore, is to some extent redundant with the description of the Kimberley district, inasmuch as the diamonds have a common source.

The part of the Vaal River which has historically been most productive of diamonds runs northeast for about 150 km, from Pniel and Kimberley to the town of Bloemhof-although the very first finds came from points farther south. About 100 km southwest of Kimberley, just below the point at which the Vaal River joins the Orange, lies the site of the De Kalk farm, where in 1867 the Jacobs children found the large crystal that started the whole South African diamond excitement; in 1869 the 83.5-carat "Star of South Africa" was found on the Zandfontein farm, also very near the junction of the Orange and the Vaal. After some early prospecting in this area, though, the early diggers moved north, to Pniel on the Vaal, developing extensive diggings at a place called Klipdrift, later Barkly West, where the gravel beds yielded many of the finest South African diamonds ever found (Williams, 1932).
As early as 1869, about 4000 diggers were at work in the Vaal and Orange Rivers (Webster, 1983). The swarming tent camps took in "a motley throng of fortune-hunters" (Williams, 1905) from the neighboring Boer lands, from the British Cape Colony, from other parts of Africa, and from abroad:

Black grandsons of Guinea coast slaves and natives of every dusky shade . . . butchers, bakers, sailors, tailors, lawyers, blacksmiths, doctors, carpenters, clerks, gamblers, sextons, laborers, loafers . . . fell into line in a straggling procession to the Diamond Fields. Army officers begged furloughs to join the motley troop, schoolboys ran away from school, and women even of good families could not be held back from joining their husbands and brothers in the long and wearisome journey to the banks of the Vaal (Williams, 1905).

Soon, of course, the kimberlite mines overshadowed the alluvial workings, but the latter continued in action nevertheless, being concentrated at points progressively farther upstream on the Vaal, i.e. to the northeast. In 1926, enormous alluvial deposits were found in high plateau country near Lichtenburg, 175 km north of Bloemhof, and 10,000 prospectors joined a first rush (Harlow, 1998). In the next year there was an "organized" rush near Grasfontein in the Lichtenburg field. A Transvaal government official standing up on a cart proclaimed the opening of a farm tract for digging, and at the drop of a flag 25,000 people rushed forward to plant their claims. The output of alluvial diamonds from the Vaal River region kept increasing well into the 20th century, with a new surge from the Lichtenberg fields after 1926, and production continues today.

From the start, Vaal River diamonds enjoyed a reputation for being unusually clear, bright, and free of fractures. Some are lightly tinged yellow, and deep orange, pale blue, brown and pink hues are found very rarely, but a large percentage of the stones are perfectly white. The commonest crystal forms are the octahedron and dodecahedron (Williams, 1905) The crystals illustrated here (a beautifully gemmy, near colorless 1.4-cm octahedron weighing 12.5 carats, and a 1.8-cm macle weighing 13.2 carats), having no doubt been found rather recently, are probably from the northern part of the Kimberley district, since, as mentioned, the general historical trend was that the alluvial workings moved northeastwards along the Vaal from the old Barkly West area near Pniel.

Finsch mine, Orange Free State, Republic of South Africa

The Orange Free State, briefly an autonomous Boer state just before the turn of the 20th century, is now a province of the Republic of South Africa. The kimberlite pipe exploited by the Finsch mine was discovered in 1960. The mine, located on the Brits Farm near Limeacre, 160 km west of Kimberley, is a major producer of gem crystals-about 25% of its diamonds are of gem quality (Webster, 1983). The discoverers of the pipe, Allster Fincham and Ernest Schwabel, had been working a claim there for asbestos, but when they found garnets in the soil they suspected the presence of underlying kimberlite (pyrope being a major "indicator" mineral). When the relevant mining law changed in their favor in 1960, they began mining diamonds.
In 1963 the entire capital of the Finsch Diamonds Company was purchased by De Beers, and two years later the mine began fullscale production. As a large open-pit mine with many benches, the Finsch produced 95,000 carats of diamonds in 1965, with production steadily increasing to 3,500,000 carats in 1985 (Maillard, 1980). The pit had reached a depth of 430 meters before underground mining commenced (Harlow 1998), and ultramodern blockcaving methods of gathering kimberlite ensure the continued importance of the Finsch mine today.

The collection illustrated here features a superb suite of 13 Finsch mine diamonds in a gorgeous array of colors including canary-yellow, orange, pink, reddish brown, colorless and black. The habits range from modified cubic to octahedral to triangular macle twins up to 6 mm in size.

Williamson mine, Mwadui, Tanzania

The Williamson mine is the largest kimberlite mine in Africa, with a main pipe eight times larger than that of the Premier mine. It has yielded diamond crystals to 240 carats; a gorgeous pink 54carat stone was cut to a gem of 23.6 carats and presented to Princess (now Queen) Elizabeth on the occasion of her marriage in 1947.

Mwadui village lies in an area of diamondiferous gravels between Shinyanga and the southern shore of Lake Victoria; some claims were pegged as early as 1910, and limited mining began in 1925 (Webster, 1983; Janse, 1996). In 1934, Dr. John Williamson, a geologist from Quebec, came to prospect in Tanzania (then British Tanganyika), and one of the last star-stories about an individual diamond entrepeneur commenced: "Every geologist dreams of discovering an important diamond mine," wrote G. J. Du Toit in an unpublished manuscript called The Williamson Story, "[and] everybody wants to own one outright. Only one man, Dr. John Thorburn Williamson . . . the discoverer and founder of the now-famous Mwadui diamond mine . . . has ever achieved both ambitions" (quoted in Maillard, 1980).

In 1940 Williamson had worked in three small, unprofitable diamond mines in Tanganyika, and had discovered a few small kimberlite pipes, but was nonetheless down to his last £100 and thinking of joining the army. But on the evening of March 6, 1940, his assistant brought him a soil sample from an abandoned survey trench near Mwadui; processing it, the two men found not only abundant grains of the indicator mineral ilmenite but also a beautiful 2-carat diamond octahedron (other versions of the discovery-story exist, as we might expect- see Janse, 1996). Soon Williamson's systematic work at the site had revealed a massive kimberlite pipe and associated diamondiferous gravels, and the Williamson mine was born. he was able to bootstrap the mine's growth from profits, and built a huge processing plant, a power station, and a township for several thousand employees. After Williamson's death in 1956, his heirs sold the mine to De Beers, and continued economic success followed Tanzanian independence in 1961, and the mine's nationalization (Maillard, 1980).

According to the present owner, Tan Range Exploration Corporation, the Williamson mine is still operating, but on a much smaller scale than previously. Through various modern exploration technologies, e.g. airborne magnetic-anomaly surveys, the company has identified several new, although small, kimberlite pipes in the area and elsewhere in Tanzania. These might be expected to compensate, at least partially, for the expected closing of the Williamson mine sometime in the fairly near future (www.tanzam 2000.com).

The Williamson mine specimen illustrated here is an attractive, nearly colorless 1.3-cm octahedron weighing 7.9 carats.

Kenema, Diamond Fields, Eastern Province, Sierra Leone

The diamond fields of Sierra Leone lie in hilly terrain north of the town of Kenema. Bounded on the west by the Sewa River and on the east by the borders of Liberia and Guinea, the region measures about 80 × 100 km and accounts for about one-third of the total land area of the tiny country. Alluvial diamonds were first found in Gboboro Stream in January 1930 by N. R. junner and J. D. Pollett of the Sierra Leone Geological Survey (Janse, 1996), and there was small-scale prospecting and mining until the end of British colonial rule in 1961. A company called Consolidated African Selection Trust (CAST), through its wholly owned subsidiary Sierra Leone Selection Trust (SLST), acquired a diamondprospecting lease over the whole country, and annual production reached one million carats by 1937 (Janse, 1996). Even during this period, as a harbinger of the chaos to come, more diamonds probably left the country illicitly than were sold by the mining company (Webster, 1983).

Sierra Leone diamonds are all alluvial, being found by timehonored methods of scouring and processing gravels in the Sewa, Gboboro, Male and other small rivers, and mining on terraces along these rivers. This is a deeply weathered terrain, with coarsegrained granitic rocks underlying the valleys and more resistant schists forming the uplands, all overlain by thick soil cover and dense vegetation. The remnants of the original kimberlite pipes crop out in only a few spots, now showing only their once deepseated roots. They must once have been large and richly diamondiferous, for even after most of the diamonds have washed out to sea, rieh alluvial deposits, including many on high banks and ledges which represent ancient drainages, are still widespread.

Quite early on in the region's history, Sierra Leone diamonds acquired the reputation for being of highest gem quality at their best, as well as very well crystallized. Many crystals, called "glasses," are sharp, lustrous octahedrons of pellucid transparency, colorless in most cases but rarely also bottle-green. The "Star of Sierra Leone," found at Yengema in 1972 and weighing 969.8 carats, is the largest alluvial diamond of gem quality ever discovered anywhere.

During the last years of British rule the villagers of the region, having learned about how to find diamonds and about their extremely high value, began illicitly collecting and selling them on a large scale, with fortune-seekers from neighboring Guinea and Liberia often joining in too. These are among Africa's poorest countries-Sierra Leone is the poorest-so the diamond mania was not surprising, but it soon threatened the overall economy of the colony. "Farmers neglected their crops and livestock to such an extent that the government had to import commodities like rice, which in normal times Sierra Leone exported. Instead of enriching the country, diamonds were threatening to ruin it. In the region of the diggings there was a severe shortage of food, and prices rose to dizzying heights" (Maillard, 1980).

The British, by issuing diamond-collecting licenses and by encouraging the villagers to dig for the official company SLST, attempted to get control of the situation. But large-scale illegal trading still went on, especially after large numbers of Lebanese merchants moved in to seize control of smuggling activities close to the border of Liberia, in whose capital, Monrovia, diamond dealers and cutters from Antwerp and elsewhere waited to buy smuggled gems at very low prices.

In 1955 the British, in co-operation with DeBeers, countered by authorizing the Diamond Corporation of Sierra Leone (DCSL) to set up a buying office in Freetown, the capital city, with smaller outposts in villages near the sources. "Miners" then could individually bring diamonds to sell at fair prices, and without risk to themselves, and the diamonds could be taxed by the government, then channeled into established international markets. The single SLST concession for all of Sierra Leone was split into two lease areas, called Yengema and Tongo (Janse, 1996).

But since Sierra Leonean independence in 1961, and especially after the country became a republic in 1971, the story of diamonds there has been largely one of civil war, mayhem, deepening poverty, cruelty, and death-one of the world's worst and least noticed "news" stories of recent decades. A series of government coups and counter-coups, these supported or undermined variously by the governments of major powers and by the forces on different sides of the civil conflict going on in neighboring Liberia, have cost tens of thousands of Sierra Leonean lives. Government and rebel forces have both typically formed their armies from underfed children and from alcohol and drug-addled young men, and all sides have employed mercenaries from the U.S., Russia and Europe to "lead" them. In one rebel offensive against Freetown between December 1998 and February 1999, at least 7,000 people died, and, in the overheated (but not necessarily inaccurate) language of one website, "Women and young girls were raped systematically . . . The population was routinely used as human shields. . . . Entire compounds of families have been emptied, the villagers lined up while the rebels jokingly decide which ones to shoot and which to let go . . ." (www.comebackalive.com). Mutilations, especially the chopping-off of arms and legs, have been practiced on a large scale, foreigners have been executed, villages have been starved, and reports of cannibalism persist.

Clearly the most common motive for all this violence is greed for the diamonds which are Sierra Leone's only significant source of wealth and accessible symbol of power. "The diamond mines were the first targets for repossession, as one of the would-be dictators hired [mercenaries] on credit, with a promise of US $500,000 a month payment in diamonds" (www.comeback alive.com). Such are the facts which lurk behind the vaguely, often glibly used term "conflict diamond"-one may or may not choose to bear them in mind while contemplating the two crystals illustrated here, a colorless, modified 1.3-cm octahedron (with a smaller "side-car crystal") weighing 7.5 carats, and a colorless triangular 1.1-cm made weighing 4.6 carats.
Between 1960 and 1996, "official" diamond production from Sierra Leone fell from 2 million to 400,000 carats per year; however, in 1996 a Canadian company was thinking of mining a small kimberlite pipe where gem-quality diamonds seem to comprise an extraordinary 60% of the total yield (Janse, 1996).

Oranjemund district, Orange River, Namibia

Oranjemund lies, as its name specifies, at the mouth ("Mund") of the Orange River, where this river empties into the South Atlantic. Since the Orange River forms the border between Namibia and the Republic of South Africa, Oranjemund is at the southernmost point of Namibia (formerly the South African protectorate known as South-West Africa, and before World War I the German colony of Deutsch Sudwest Afrika). At Oranjemund, the Namdeb Diamond Corporation Limited (owned jointly by the Namibian government and De Beers) maintains a fleet of earth-moving equipment "nearly as large as that owned by the United States army" (Maillard, 1980), and uses it to conduct a mammoth beachmining operation for diamonds.

"Beach" diamonds were first detected along this coast in 1908, near Luderitz, where a railroad worker found a few small crystals in the sand dunes. Soon, discrete beach deposits were being found along a 60-mile stretch north of the mouth of the Orange, and the Germans were mining considerable numbers of small but highquality diamonds. When South Africa took control after World War I, the deposits were sold to Consolidated Diamond Mines (CDM), which was transferred to DeBeers in 1929; the present Namdeb Corporation was organized in 1994. Its current operations include beach-mining, terrace-mining, and seabed-mining-all flourishing nicely, and imparting a new sense to the old term "alluvial diamonds."

For a while geologists wondered whether these marine diamonds had come from kimberlites on the sea floor, or whether they had been transported oceanwards from the great kimberlite swarms of the inland Kalahari Craton. But it is now quite certain that kimberlites do not occur in the ocean basins, only in continental cratons, and moreover a mere glance at a stream-drainage map of southern Africa makes it clear that huge numbers of diamonds from inland kimberlites must have been transported to the sea by the Orange River system (including tributaries such as the Vaal); further, it has been noted that the sizes of the marine diamonds diminish regularly as the distance from the mouth of the Orange increases. Presently it is estimated that over the past 100 million years, up to 1,400 meters have been eroded from the land surface of South Africa and Namibia, and that of all of the diamonds released to the streams by the weathering of the kimberlites, only 10% stayed behind in inland alluvial deposits, the remaining 90% having been carried to, and out into, the ocean. And since the ocean waves shatter the poorer-quality diamonds, 90-95% of marine diamonds are of gem quality (www.amnh.org/exhibitions/diamonds).

Terrace mining for diamonds at Oranjemund takes place well above the high-water level and up to 3 km inland, and seabed mining, carried out by suction-dredging from huge offshore barges, operates more than a mile out from the mouth of the Orange. More important than either of these is beach mining. In the first stage of this process, massive earth-moving equipment removes loose beach-sand overburdens to depths of up to 80 feet, exposing ancient beach terraces as much as 65 feet below present high-water levels. The terraces are broken up and bulldozed into rubble-piles until the tough, irregularly configured bedrock schists are laid bare: this is the level most avidly sought, since the gravels left in the potholes and crevices here have concentrated most of the diamonds.
Backtrenchers with digging buckets gouge out some of the gullies, but mining from this point is largely a matter of hand work: miners known as bedrock cleaners dig, shovel, and sort the highly diamondiferous residual gravels, until the whole schist floor is swept clean (Maillard, 1980). The technology is efficient, and potential yields from the "Oranjemund district" are vast-in 1995 alone, such beach deposits produced 1,300,000 carats of diamond crystals (www.amnh.org/exhibitions/diamonds).

Similar beach deposits have been located in Namaqualand, South Africa, south of the mouth of the Orange, as well as much farther north, on the "Skeleton Coast" of Namibia (Webster, 1983). It is most likely, however, that the specimen illustrated here (a gemmy triangular made twin 1.3 cm across, weighing 4.1 carats) came from somewhere not too far north of Oranjemund-and that the working from which it came has long since been buried again by tide-borne sands.

Bangui region, Central African Republic.

Although only a tiny fraction of the world's diamonds comes from the Central African Republic, diamonds are this poor, landlocked former French colony's principal resource. The colony (which is partially underlain by a small craton), was once known as Ubangi-Chari; it lies just north of Zaire, the latter also known as the Congo Republic. Neither state should be confused with the former French Congo, now the People's Republic of Congo, lying just to the west of Zaire (devotees of dioptase will be familiar with these confusions). The Ubangi (or Oubangui) River marks the border between Zaire and the Central African Republic, and Bangui is a town on the river's north bank. The "Bangui region" (source of the crystal illustrated here, a 1-cm yellow cube weighing 4.1 carats) corresponds to a diamond-producing area between Bangui and Berberati, in the southwestern part of the country (Maillard, 1980; Webster, 1983).

Here, diamonds are recovered by clearing heavy forest and jungle vegetation, then removing a thick bed of topsoil to reach diamond-bearing alluvial gravel; there is also some mechanized dredging in beds of the region's numerous rivers and streams. Further diamond-related developments may follow when the parent kimberlite or lamproite pipes (if they still exist) are finally located in the Central African Republic.

Northern Lunda Province, Cuango River area, Angola

Angola produced 1.8% of the world's diamonds in 1996 (www.amnh.org/exhibitions/diamonds), and a high proportion are of gem quality. Counterbalancing these upbeat observations, though, is the fact that civil wars and insurgencies have intermittently troubled Angola ever since independence from Portugal was declared in 1975. Consequently, as in the case of Sierra Leone, diamonds known to be from Angola may be "conflict diamonds." At least half of all diamonds found in the country are gathered and sold illicitly (Janse, 1996). Even when there is no fighting, demobilized soldiers generally prefer to dig gems rather than return to bare-subsistence farming.

The Angolan diamond regions are all in the northern part of Lunda Province, in the country's northeastern corner, adjoining Zaire,. In fact, the first discoveries of alluvial diamonds, in 1911/ 1912, were byproducts of exploratory surveys just to the north, in what was then the Belgian Congo. A series of parallel rivers run from south to north through Lunda Province before passing into Zaire, and diamonds have been found in many of them. The Cuanga River, forming the border between Lunda Province and Malanje Province to its west, is the largest of these rivers, and had produced about 80% of Angola's diamonds as of 1998 (Harlow, 1998). It is possible, however, that the stated source of the lovely 1-cm yellow crystal illustrated here,"Cuango (or Kwombo) River," is merely a geographically convenient term, and that the diamond was found in one of the region's smaller rivers (candidates include the Chicapa, Luachimo, Chiumbe, Luana and Lembe).

Creative geological fieldwork by R. Delville in the early 1950's succeeded in establishing that diamondiferous gravels and conglomerates were concentrated along two parallel faults in a buried fault-graben structure in Lunda Province, and inferences could then be drawn concerning where the original kimberlite sources lay concealed in the forested wilderness of the province. The first of the kimberlite pipes was found near the Chicapa River in 1952; it is now known to be one of the largest in the world (Maillard, 1980), and one of about 600 pipes in northern Lunda (Harlow, 1998). Ongoing mining and prospecting is in the hands of a consortium, Consorcio Mineiro de Diamantes (Condiama), whose members include De Beers, the government of Angola, and an earlier company called Diameng (Companhia de Diamantes do Angola), which had begun to look for diamonds during Portuguese colonial times.

Ghana

Although Ghana is not represented by any of the diamonds in the collection featured here, it is the locality for the large and amazingly modified cube shown on the cover of this issue, from the collection of Mike Scott. In 1911, British prospectors found small numbers of alluvial diamonds in what was then the colony called the Gold Coast-more famous in history both for its gold and for its infamous slave-trading ports-on the Gulf of Guinea. As of 1980, 3 million carats of diamonds were being produced annually, 85% of the output being merely of industrial grade (Maillard, 1980). In 1996 the country accounted for 0.7% of world diamond production (www.amnh/exhibitions/diamonds).

Alluvial diamond deposits in Ghana are concentrated in the Birim valley, in the Akwatia region midway between the capital city of Accra and the town of Kumasi (Maillard, 1980)-this is the likely provenance of the cover crystal.

The Future of Diamond Mining

Levinson et al. ( 1992) estimate that the total world production of diamonds, both gem and industrial, between remotest antiquity and the year 1990 was 2,213,875,000 carats, equivalent to 450 metric tons weight. This is, they say, a conservative estimate, since it rounds up only slightly from official figures to take into account unreported, illicit production. As mineral species go, even gempotential species, diamond is not really rare-how many tons of jeremejevite or sinhalite do you suppose have been found?-but its enduring appeal, not to speak of its many industrial uses, makes the securing of further supplies a pressing concern.
Since 1870, Africa has spoiled us: in that year, as mining was just beginning at Kimberley and on the Vaal River, only 300,000 carats of diamonds were produced worldwide, but in 1920, 3,000,000 carats were produced, the tenfold increase being entirely due to new production from African sources. Although the classic African kimberlite mines are now in decline (and some are closed), new African mines, Russian mines, and most recently the Argyle mine in Australia have so far kept worldwide production growing rapidly: 42,000,000 carats were produced in 1970, and more than 100,000,000 in 1990 (Levinson et al, 1992). But now several Russian mines, the Williamson mine in Tanzania, and even the Argyle mine are well past their primes-if we keep up the present rate of consumption, where are diamonds to come from in future decades (aside from the vast stockpiles held by the Russian Diamond Fund)?

One plausible speculation is that more and more of them will come from the sea. Marine diamond mining off the Atlantic coasts of South Africa and Namibia was pioneered by two small companies in 1954. Then, in the early 1960's, a Texas oilman named Sam Collins founded a company called the Marine Diamond Corporation, now in the capable, high-tech hands of De Beers Marine (Pty) Ltd. This company currently dominates the available offshore lease areas, which extend up to 5 km out from the shore (Gurney et al, 1991). There are several positive indications about this diamond source: for one thing, a conservative estimate of reserves in the African marine deposits is 1.5 billion carats-almost three-quarters of total world production since antiquity-and, for another thing, 90-95% of the diamonds are of gem quality, natural "sorting" having destroyed the inferior stones along the way between the original drainages of the kimberlites and final deposition on the continental shelf. To put it in terms of another statistic, these deposits contain at least 100 times as many gem diamonds (by weight) as are presently being used each year in jewelry (Levinson, et al, 1992). However, diamonds recovered by relatively simple suction equipment, and by divers, in shallower waters are vastly outnumbered by deeper-water diamonds, and these are difficult and expensive to find and retrieve. Much technical progress is being made, but deep-marine diamond mining is still only marginally profitable. It may also be true that the South African/ Namibian marine diamond deposits are an anomaly in the world, since they result from the uniquely favorable combination of a rich inland diamondiferous craton, deep weathering of the craton, and stable drainage over a very long time to a nearby ocean. Prospectors have eyed the Arctic waters north of the Siberian and Canadian cratons, and some sites in the Gulf of Guinea, but climatic as well as geological factors would seem to preclude mining in these areas, even if they should prove to hold diamonds.

Although they acknowledge the importance of the southern African marine fields, and although they regard some inland alluvial diamond deposits, particularly in Angola, as promising, Levinson et al. (1992) predict that the most significant new diamond sources of the 21st century will be newly discovered kimberlite pipes in Siberia and northern Canada. Economically viable kimberlites, they point out, are amenable to large-scale mining and discouraging to illicit "pirates": two-thirds of world diamond production in 1990 came from just eight large kimberlite mines. The Russian and Canadian cratons are vast, and huge swarms of diatremes may well lurk under the glacial cover in under-explored or unexplored regions (the very rich diatreme now being exploited by the Ekati mine remained successfully camouflaged for a long time under the glacial meltwater of Lac de Gras).
Levinson et al. also point to the geological favorability of Antarctica, where a large craton lurks under the ice cover. Perhaps by the end of this century some technology will have evolved for getting at diatremes there. And Janse (1996) suggests that Africa may not only continue to be a major diamond producer, but may again become the major producing diamond province of the world, perhaps thanks to technological breakthroughs at the marine deposits, or perhaps also to new kimberlite discoveries in central and western Africa, where alluvial mining so far has been the only important kind.

As a mineral collector, one might wistfully regret that almost all of the people who customarily seek or mine or study or write about diamonds are interested in them solely for their industrial or gemstone uses, or as objects of scientific research. It would be interesting (though probably depressing) to know exactly how many euhedral, uncut crystals of diamond are preserved today, from throughout the course of the long history of human obsession which has been sketched here. The fine crystals in the private collection illustrated here provide a wonderful glimpse of a unique species in its original state.

Acknowledgements

My thanks to the owner of the specimens featured here for making them available for study and photography, and to Bill Birch for reviewing the manuscript and making helpful suggestions. My thanks also to Wendell Wilson for executing the photography, for preparing the other illustrations, for providing information on early collectors, and for locating references in the Mineralogical Record Library. It should be noted that the Record Library was an invaluable resource in the preparation of this article.

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Illicit diamonds: Africa's curse

Just as the history of Arab States is intimately tied to the discovery of oil in the region, the discovery of diamonds in Africa has not only impacted the continent's history, but has been one of the leading causes of conflict.

The link between diamonds and conflict in Africa and the role of international players in the illicit diamond trade were recently discussed at a seminar in Nairobi, Kenya, on resource-based conflicts organized by the Society for International Development's East Africa Chapter. It is interesting to note that Africa's most conflict-ridden countries--Angola, Sierra Leone and the Democratic Republic of the Congo--are also the most diamond-rich countries on the continent, as well as the most poor and under developed. Conflict or "blood" diamonds have fuelled wars and led to the massive displacement of civilian populations in many African nations. While conflict diamonds represent a small proportion of the overall diamond trade, illicit diamonds constitute as much as 20 per cent of the annual world production. The level of illegality gives an opportunity and a space for conflict diamonds.

The link between diamonds, poverty and conflict is evident in countries such as Sierra Leone, where the rich alluvial diamond fields of the Kono District and Tongo Field were among the most prized targets of the Revolutionary United Front (RUF). In 2000, Partnership Africa. Canada (PAC) published a report entitled "The Heart of the Matter: Sierra Leone, Diamonds and Human Security", which placed much of the blame for the civil war in the country on diamonds, describing them as "small bits of carbon that have no intrinsic value in themselves, and no value whatsoever to the average Sierra Leonean beyond their attraction to foreigners".

The report recounts the corrupting of Sierra Leone's diamond industry, from peak exports of 2 million carats a year in the 1960s to less than 50,000 carats by 1998. The country's despotic President during much of this time, Siaka Stevens, had tacitly encouraged illicit mining by becoming involved in criminal or near-criminal activities himself. When the RUF began waging a war in 1991, Liberian leader Charles Taylor acted as mentor, trainer, banker and weapons supplier for the movement. The RUF also took on the role of diamond supplier to the illicit international trade. "It is ironic", says the report, "that enormous profits have been made from diamonds throughout the conflict, but the only effect on the citizens of the country where they were mined has been terror, murder, dismemberment and poverty".

The PAC report supports the idea that there was virtually no oversight of the international movement of diamonds. In the 1990s, for instance, billions of dollars worth of diamonds was imported into Belgium from Liberia, even though the latter produces very few diamonds. This can only be explained by the fact that big and small companies were colluding in the laundering of diamonds in West Africa, using Liberia as the conduit country. Much of the laundering was done by local Lebanese traders who have been living in West Africa for over a century.

Lebanese immigrants began arriving in West Africa as refugees fleeing the hardship caused by the silk-worm crisis which struck Lebanon in the mid-nineteenth century. Among the earliest recipients of those immigrants were Senegal and Sierra Leone, then under European colonial rule. According to Lansana Gberie, a researcher who has written about the Lebanese connection in Sierra Leone's diamond trade, since the 1950s, "diamonds have been the linchpin of Lebanese business and a range of subterranean political activities".

In her paper, "War and Peace in Sierra Leone: Diamonds, Corruption and the Lebanese Connection", published by the Diamonds and Human Security Project in 2002, Gberie describes the beginnings of the Lebanese trade in diamonds: "Diamonds were discovered in Kono District, in eastern Sierra Leone in 1930, and that same year, as word of the discovery spread, the first Lebanese trader arrived in Kono and set up shop, ahead of colonial officials who did not want to establish a district office there until two years later. They were also ahead of the British-owned Sierra Leone Selection Trust, which was granted exclusive diamond mining and prospecting rights for the entire country in 1935. From that time until 1956, when an alluvial diamond mining scheme was enacted, it was illegal for anyone not working for the Trust to deal in any way with diamonds. However, illicit mining activities were rampant, with many Lebanese subsequently settling in Kono and funding Africans to mine and sell their finds to them."

In the 1950s, the illicit diamond mining and smuggling increased dramatically, and it was estimated that 20 per cent of all diamonds reaching the world's diamond markets were smuggled from Sierra Leone, largely through Liberia and mainly by Lebanese and Mandingo traders. In later years, civil war often revolved around the control of this illicit trade. In 2002, a UN Expert Panel reported that the then "interim" leader of the RUF, Issa Sesay, had flown to Abidjan late in 2001 with 8,000 carats of diamonds that he had sold to two traders of undisclosed identity, who were apparently using a Lebanese businessman to run errands for them between Abidjan and the Liberian capital, Monrovia. Some reports suggest that the UN peacekeeping force in Sierra Leone may have also become involved in the RUF illicit diamond trading.

In 2001, shortly after the 11 September attacks in New York and Washington, D.C., the Washington Post found another link in this most secretive and highly lucrative trade--that of international terrorists. In an article published on 2 November 2001, war correspondent Douglas Farah stated that the Al Qaeda network "reaped millions of dollars in the past three years from the illicit sale of diamonds mined by rebels in Sierra Leone" and that three senior Al Qaeda operatives had visited Sierra Leone at different times in 1998 and later. He further claimed that the West African Shi'ite Lebanese community was sympathetic to Hezbollah and often served as a link between the RUF rebels and Al Qaeda. However, according to Gberie, much of the evidence linking West Africa's Lebanese community to global terror networks is largely "anecdotal and circumstantial".

In the last few years, however, the illicit diamond trade has come under scrutiny from many quarters, which makes it much more difficult for middlemen and smugglers to operate. Since 1999, PAC has undertaken a programme of policy research, education and advocacy to ensure that the international diamond industry operates legally, openly and for the primary benefit of the countries where the diamonds originate. It has also extensively published reports that have uncovered the secret dealings and James Bond-style manoeuvres of the middlemen and smugglers in the industry who operate often with the full knowledge and approval of Governments (or rebel movements), and act as conduits for diamonds smuggled from neighbouring countries.

In May 2000, an international certification process for rough diamonds, known as the Kimberley Process, was initiated by the Government of South Africa. Concerned about how diamond-fuelled wars in Angola, Sierra Leone and the Democratic Republic of the Congo might affect the legitimate trade in other diamond-producing countries, more than 35 nations have been meeting on a regular basis to develop the system, which was established in 2003.

In Sierra Leone, the diamond certification system was instituted in October 2000, four months after the UN Security Council passed a resolution that banned diamond exports until a certification system was set up. In the twelve months after the system was introduced, legal exports rose from $1.3 million to $25.9 million worth of diamonds. However, PAC believes that many of the better quality diamonds are still being smuggled and are not going through the official certification system. In other words, the illicit diamond trade continues to operate through informal agreements that are sealed with a nod, a wink and no paper trail.

Author Rasna Warah, a freelance writer based in Nairobi, is a Board member of the East Africa Chapter of the Society for International Development.

COPYRIGHT United Nations Publications, COPYRIGHT Gale Group

Diamonds are forever - and greed

MANY SEE EXPENSIVE diamonds as the perfect gift for their significant others. Yet, couldn't some other gem have the same impact? There is an extraordinary logic to the diamond trade: Diamonds are presumed of value because they are pricey. Consumers are told they are pricey because they are rare and expensive to cut. Are they really? After all, flawless diamonds can be produced in a laboratory. A "mined" diamond and a "lab" version are tough to tell apart. Little wonder, since both are crystallized carbon. Of course, concern over the price of gems pales in comparison to the horrible sight of children whose arms have been amputated by the thugs who tam diamond mines in West Africa, or the knowledge that Al Qaeda trades in diamonds purchased from these same mines.

Responding to the outcry of its citizens, Congress passed the Clean Diamond Trade Act in 2003 to guarantee that gems purchased in the U.S. be free from all human rights abuse. Is this legislation working? Are the diamonds in our stores guaranteed to be clean? I set out to answer these and other questions using the Freedom of Information Act. I searched the records of the Justice and State Departments for information on this lucrative trade and on De Beers, the company that controls 65% of the world's diamond supply. In 1942, the Justice Department began an investigation of De Beers that is still ongoing. I went through thousands of pages of intercepted cables, spy reports, Nazi documents, and eye-opening mail. These brutal diamond wars have been going on fur decades. Moreover, terrorists have long used the precious stones to fund their egregious activities.

Documents reveal highly secretive price-fixing operations that run rings around the Justice Department, Congress, and the White House. The strategy is quite simple, actually: American diamond merchants pick up their supply from De Beers in London where U.S. laws banning exploitative price fixing do not apply. De Beers moves diamonds along clandestine routes used by drug barons and arms merchants. I traced these trails, I found De Beers has its own area in Switzerland's Zurich Airport where, as a customs official explained to me, it can fly in a diamond from Africa, and, within a day, legally arrange for it to be given papers identifying it as Canadian. The United Nations claims that this tactic makes it near impossible to trace terrorist-linked diamonds. De Beers, incidentally, is controlled by a family company registered in Liberia.

International trading statistics show that diamonds sent from Switzerland to the United Kingdom surprisingly multiply by three times en route. In 1982, for example, UK customs recorded 10 times more stones arriving from Switzerland than Switzerland said it had sent. Some years, by similar means, thousands of gems vanish into thin air. As for the diamond-producing countries of South Africa, Namibia, and Botswana, their gems may seem to disappear from international circulation overnight.

After reviewing documents and traveling around the world to investigate the many leads they supplied, I wrote a proposal fix a television special called "The Diamond Empire." It appeared in 1994 as a feature-length "Frontline Special" on PBS and as a three-part BBC series. Filming was not an easy project to complete. Everywhere I went. De Beers had phoned merchants telling them not to speak with me. Gradually, though, I untangled The diamond cartel's web, shooting footage in India, Europe, and the U.S. Then a gang broke into my home and assaulted me, shattering several of my facial I bled heavily from the wounds head. The next day, there was a surprise attempt to take over the documentary I withstood this, but medical complications soon set in. I spent two months in the hospital. For two of those weeks, I was in critical condition. I could not edit the film myself. PBS cut it to my script, but the BBC censored its version under heavy pressure from De Beers. When I came out of the hospital, I was determined to complete my investigation and publish the findings uncensored.

Diamonds once were genuinely rare--about 140 years ago--after the diamond mines practically ran dry in India. Then diamonds were discovered by the thousands literally sparkling in the moonlight in southern Africa. Merchants who had invested huge sums of money in the few remaining diamond mines in India panicked. They feared their investments would plummet in value. So, they funded South African politician Cecil Rhodes to set up De Beers. He had all the cash needed to buy up the diamond deposits of South Africa. In return, he agreed to sell the entire output to the "Diamond Syndicate" comprised of these same merchants. Thus, they kept the price high. In the 1930s, the Oppenheimer family gained control over De Beers and the Diamond Syndicate.

I first became interested in diamonds in 1979. I was working on civil rights issues with Aborigines in the far northwest of Australia when a major diamond deposit was found nearby in a sacred valley called Barramundi Dreaming, where for centuries women had gone to pray and meditate. Some of these women took me to see the site before it was destroyed by the diamond rush. There was a beautiful, sparkling stream surrounded by fat-trunked boab trees. When I looked into the water, there were hundreds of diamonds, lying like glossy pebbles in its bed. Later, I learned from local geologists that there were up to 27 carats of diamonds in every ton of rock underlying the stream's headwaters. Today, this locale is an enormous pit, full of excavators and tracks. It is producing up to eight tons of diamonds a year at a cost of less than $10 a carat.

Supposedly, De Beers was reaping a mere one-fifth of a carat for every ton of mined rock in Africa. However, Canada has diamond deposits with four carats per ton, and some Russian mines produce 10 carats a ton. Why then were the South African mines doing so poorly? I met a diamond prospector who had worked as an overseer in De Beers' mines. He told me that sometimes they broke into pockets where gems were so plentiful that they would tumble out onto the ground. When this happened, the overseers literally would shovel up the diamonds into buckets.

Was I being spun a story? I went to South Africa to investigate and met with miners and geologists working for De Beers. They confirmed the details. In fact, I heard tales of more than 3,000 carats of diamonds tumbling out of the rocks within the De Beers mines. In Kleinzee, I visited a vast mine on the wild Atlantic coastline, where diamonds lie under giant sand dunes roamed by ostriches and edged by fierce surf. The wife of the mine's chief geologist took me on a tour. She commented on the fine gems under the dunes and on the nearby sea floor, washed from dormant volcanoes that hi ancient times spilled diamonds onto the Earth's surface. Offshore, De Beers' vessels were sucking up gems from the seabed. On its first trip, one vessel grabbed up nearly 5,000 large stones in a week. These are canned like peas to keep them secure. The head of the South African Diamond Board imparted, "We do not shout it from the rooftops, but diamonds are not rare, except for some qualities."

I watched the mineworkers dig. Giant excavators removed the sand. Some laborers used vacuum hoses connected to large yellow safes on wheels to swallow up exposed diamonds. Others formed lines, bending over to examine every tiny crevice in the rocks. In one hand they held a brush, in the other a metal prong, thus earning the nickname "bedrock cleaners." They are paid so little that De Beers calculates that it costs a mere 40 cents a yard to clean a beach. The company recently agreed to pay a minimum of $50 a week, but not for long. It is replacing the union mineworkers with subcontracted laborers to be paid only $20-30 a week. De Beers officially calculates that each one of its 3,000 miners at Kleinzee produces, on average, over $1,600 worth of diamonds every seven days. Many maintain that this estimate is quite conservative.

I asked a group of black diamond mineworkers if they bought their loved ones en gagement rings. They laughed. "De Beers brings us divorce, not love!" they claimed. They explained that since they were in the lowest wage bands, they were not entitled to married housing. Instead, they lived in single men's barracks. If their wives got a job in the mining town, say as a cleaner or cook, they had to stay in the single women's quarters. They were punished if found to be sleeping with their partners. This comes as no surprise. Remember, De Beers helped create apartheid in order to gain control over its workforce.

The mine has very tight security. If an ostrich accidentally is killed on the grounds, its corpse has to go to company security to make sure it has not swallowed a diamond. The man who operates the X-ray machine revealed that he had to give workers a whole-body scan every day in order to ensure that nothing was smuggled out. He confessed he concealed the health danger by not recording all the X-rays in the mine's records. I subsequently investigated a larger coastal mine--covering hundreds of square miles--in Namibia, known historically as "The Forbidden Zone." I found working conditions there much the same.
I visited De Beers' inland mines as well, including one where diamonds literally were picked out of asbestos rock. The dust was so thick that miners sometimes could not see their fingertips. For protection, all they bad was a simple nosebag--a piece of cloth that was black with dust within 20 minutes. Medical statistics were unobtainable; they were kept confidential by De Beers. The company also is able to conceal diamond deposits by having them secluded inside game reserves, where mining is forbidden. The company allegedly trucks in antelope for the sake of appearances. Another major deposit was concealed within the Kalahari Desert in Botswana, on lands traditionally owned by people with the most ancient culture surviving in our world, that of the Bushmen. In 2002, the Botswanaan government evicted the entire population, maintaining it was for assimilation purposes. The Bushmen say they have been moved to "death camps." De Beers, however, has no intention of mining these diamonds any day soon. They have placed a concrete slab over the mining shaft. De Beers Chairman Nicky Oppenheimer even boasts that the concrete is so thick that "I can land my helicopter on top of it."

Nine in 10 of the world's diamonds are cut in India by individuals who were paid 40 cents per gem. Those wages were slashed to 20 cents in 2001. Today, the average pay to cut and polish a diamond for the American market is 23 cents. Eight-year-olds are cutting diamonds. This industry is hazardous because of fast-moving belts and airborne diamond dust. I estimate that consumers are paying at least 10 times too much for the diamonds they purchase--but that is nothing compared to the cost to exploited diamond workers (many of them children) around the world.

Author Janine Roberts is the author of Glitter and Greed: The Scorer World of the Diamond Cartel.

COPYRIGHT Society for the Advancement of Education, COPYRIGHT Gale Group