Background (Encyclopedia of Global Resources)
Diamond is the hardest known substance, natural or artificial, and is number 10 on the Mohs hardness scale. The close-packed cubic arrangement of the atoms gives diamond its unique hardness. It also has the highest thermal conductivity of any known substance.
Historical records of diamonds date back to 3000 b.c.e. In recent centuries, Golconda diamonds of India dominated diamond production until the early eighteenth century. In 1725, Brazilian diamond mines gained prominence. South Africa’s “great diamond rush” began in 1867, and in 1890, the De Beers company consolidated dozens of mining communities in Africa. Diamond derives its name from the Greek word adamas, which means “unconquerable.”
Almost all of the world’s diamond production comes from Africa, most notably South Africa. Other diamond-producing countries include Angola, Borneo, Ghana, Guyana, Namibia, Sierra Leone, Tanzania, Venezuela, Congo, Brazil, and Russia (Siberia). In the United States diamonds have been found in Arizona, Arkansas, Montana, and Nevada.
(The entire section is 151 words.)
Technical Definition (Encyclopedia of Global Resources)
The atomic number of carbon is 6, and its atomic weight is 12.011. It belongs to Group IVA of the periodic table of elements. Gem diamonds have a density of 3.52, although “black diamonds” have a density of about 3.15. Diamond slowly burns to carbon dioxide at a very low temperature (900° Celsius).
Diamond’s high refractive index (2.417) and strong dispersion property (0.058) guarantee its supremacy as a gemstone. However, only about one-fifth of all the diamonds mined qualify as gems. Most of the remaining uncut diamonds are used by industry. Tunnel boring and oil-well drilling equipment uses diamond-studded rotary bits. Carbide grinding wheels, abrasion-resistant cutting tools, and glass-etching and glass-cutting equipment use industrial-quality diamonds. Some dentists and surgeons use diamond-headed scalpels to cut delicate bones and tissue. Diamond coatings are used in integrated circuits, prosthetic devices, and biosensors. Diamond is the most important industrial abrasive, and industry uses about 80 percent (by weight) of all diamonds produced. However, this represents only about 30 percent by value.
(The entire section is 159 words.)
Creation and Properties of Diamond (Encyclopedia of Global Resources)
About 30 meters inside the Earth, exceedingly high pressures and temperatures (more than 1,400° Celsius) cause magnesium-rich rock melts to crystallize, resulting in the formation of diamonds. Samples of deep mantle material contain diamonds as a natural component. The reaction of groundwater with hot, magnesium-rich, deep mantle material aided by carbon dioxide leads to the formation of a rock called kimberlite. Kimberlite is an igneous rock that is ultrabasic and contains very little silica. Kimberlite is the world’s principal source of diamonds. Explosive eruptions create craters filled with deep mantle rock formations and permit diamond-containing rocks to surface through cracks. These are known as diamond pipes (sometimes incorrectly called “volcanic necks”).
In addition to being the hardest substance, diamond is an excellent conductor of heat. Because diamonds possess the highest thermal conductivity of any known substance, industrial-quality diamonds are used in abrasion-resistant cutting tools. Almost all diamonds are nonconductors of electricity. However, some diamonds permit the passage of electric current when bombarded with radiation. Diamond crystals form as octahedrons, dodecahedrons, and cubes. A well cut gem can reflect almost all the light that it receives. This quality is called “luster.” In addition, it can disperse or separate the colors of the spectrum while reflecting the...
(The entire section is 211 words.)
Occurrence of Diamond (Encyclopedia of Global Resources)
Mining experts have discovered hundreds of diamond-containing dikes and pipes in Transvaal, Kimberley District, and Free State (formerly Orange Free State), South Africa; Yakutsk, Siberia; Shinyanga, Tanzania; Mbuji-Mayi, Democratic Republic of the Congo; Yengema, Sierra Leone; Murfreesboro, Arkansas; and several other locations. However, it is not economically feasible to carry out “mine-at-depth” procedures in most of these pipe mines. Unless new pipes are discovered, natural diamonds may be exhausted relatively soon.
The erosion of diamond pipes over millions of years has resulted in secondary deposits called alluvial or placer deposits. These deposits contribute significantly to the world’s total diamond production. Most alluvial diamonds are recovered from stream gravel, but beach gravel is also a good source. Diamond-containing beach gravel extends to the depths of the ocean floor, although there is no economical means of recovering diamonds from ocean depths. Diamonds are also found in glacial tills. Minute quantities of microscopic diamonds have been found in meteorites as well.
(The entire section is 159 words.)
Synthetic Diamonds (Encyclopedia of Global Resources)
On February, 15, 1955, the General Electric Company announced its success in creating a synthetic diamond. Since then synthetic diamonds have become widely used in grinding wheels and a number of other applications. They are normally single crystals, usually octahedral in shape. Since they have several cutting edges, they are preferred over natural diamonds for industrial purposes. To make them, graphite (another form of crystalline carbon) is subjected to very high temperatures and pressures. Extreme pressures as high as 296,076 atmospheres (about 30 billion pascals) and temperatures as high as 3,037° Celsius (water boils at 100° Celsius) have been used, depending upon the actual process. Two common procedures are shock conversion and static conversion. Synthetic diamonds are also manufactured by the static crystallization of certain alloys and molten metals.
Synthetic diamonds, normally black in color, are produced in grain sizes that are about one-hundredths of a centimeter in diameter. It is possible to “grow” larger, gem-quality synthetic diamonds, but the process is too costly to be feasible. Synthetic diamonds are chemically and crystallographically identical to the naturally occurring diamond gemstone. “Imitation diamonds,” on the other hand, are completely different from either synthetic or genuine diamonds. Imitation diamonds do not possess either the hardness or the crystallographic structure of the...
(The entire section is 228 words.)
Cutting Diamond (Encyclopedia of Global Resources)
After mining and recovery, gem-quality diamonds are separated from industrial-quality ones. A rough, uncut diamond looks like a dull piece of glass. Precise cutting, artful grinding, and skillful polishing of the diamonds yield outstanding gems, and some have attained historic fame. Diamond cutting began in India and was later perfected in Italy. Only a diamond can cut a diamond: Diamond crystals are cut, cleaved, shaped, and polished by “diamond dust on a lap.” World-famous diamond cutting establishments are concentrated in Antwerp, Belgium, and in Amsterdam, the Netherlands. India and Israel have also emerged as world leaders in diamond cutting. The most popular cut is the “brilliant cut,” which has a round shape with fifty-eight facets. Gem-quality diamonds are classified according to their weight, clarity, color, and absence of flaws. The weight of a diamond is measured in carats; a carat equals 0.2 gram, or about 0.00704 ounce. Transparent, colorless, and light blue diamonds are extremely rare and are considered to be highly valuable gems. There are red, pink, blue, and green diamonds. Diamonds with a yellow tint are more common. As the tint becomes increasingly yellowish, the value decreases. Industrial-quality diamonds are gray, brown, or black and are almost opaque. They are gems of poor quality.
(The entire section is 204 words.)
Famous Diamonds (Encyclopedia of Global Resources)
The largest diamond ever found, the Cullinan, was found in 1905 in the Premier Mine, Transvaal, South Africa, and weighed 3,106 carats. This stone was cut and polished into several gems, two of them world famous: The 530-carat Star of Africa and the 309-carat Star of Africa II are among the British crown jewels, housed in the Tower of London. These are the world’s largest cut diamonds. The cutting of the Cullinan also resulted in another seven large gems and ninety smaller ones.
The 109-carat Koh-i-Noor (“mountain of light”), set in the British crown itself, is the oldest diamond gemstone known to historians; its history has been traced back to 1304. This diamond had its origin in India, and it originally weighed 186 carats before Queen Victoria had it recut in 1852. Many believe that the largest blue diamond, the 44.5-carat Hope diamond, presently in the Smithsonian Institution, adorned the eye of an Indian god. Other world-famous diamonds India has contributed include the Regent or Pitt (140 carats, presently in the Louvre, France); the Orlov (200 carats, presently in Russia); the Florentine (137 carats, location unknown); and the Great Mogul (280 carats, location also unknown).
(The entire section is 187 words.)
Further Reading (Encyclopedia of Global Resources)
Balfour, Ian. Famous Diamonds. 4th ed. London: Christie’s, 2000.
Chatterjee, Kaulir Kisor. “Diamond.” In Uses of Industrial Minerals, Rocks, and Freshwater. New York: Nova Science, 2009.
Green, Timothy. The World of Diamonds. New York: Morrow, 1981.
Hart, Matthew. Diamond: A Journey to the Heart of an Obsession. New York: Walker, 2001.
Hazen, Robert M. The Diamond Makers. New York: Cambridge University Press, 1999.
Maillard, Robert, Ronne Peltsman, and Neil Grant, eds. Diamonds, Myth, Magic, and Reality. New rev. ed. New York: Bonanza Books, 1984.
Nazaré, M. H., and A. J. Neves, eds. Properties, Growth, and Applications of Diamond. London: IEE, 2001.
O’Donaghue, Michael. Gems: Their Sources, Descriptions, and Identification. 6th ed. Oxford, England: Butterworth-Heinemann, 2006.
Prelas, Mark A., Galina Popovici, and Louis K. Bigelow, eds. Handbook of Industrial Diamonds and Diamond Films. New York: Marcel Dekker, 1998.
Zoellner, Tom. The Heartless Stone: A Journey Through the World of Diamonds, Deceit, and Desire. New York: St. Martin’s Press, 2006.
American Museum of Natural History. The Nature of Diamonds. http://www.amnh.org/exhibitions/diamonds
Natural Resources Canada. Canadian Minerals Yearbook, Mineral and Metal...
(The entire section is 204 words.)
Diamond (World of Earth Science)
Diamond is cubic native carbon with the same composition as graphite, but with different structure. It is the hardest mineral (10 on the Mohs' scale), with the highest refractive index of 2.417 among all transparent minerals, and has a high dispersion of 0.044. Diamonds are brittle. Under UV light, the diamond frequently exhibits luminescence with different colors. It has a density of 3.52 g/cm3. The mass of diamonds is measured in carats; 1 carat=0.2 grams. Diamonds rarely exceed 15
carats. Diamonds are insoluble in acids and alkalis, and may burn in oxygen at high temperatures.
Nitrogen is the main impurity found in diamonds, and influences its physical properties. Diamonds are divided into two types, with type I containing 0.001.23% nitrogen, and type II containing no nitrogen. If nitrogen exists as clusters in type I diamonds, it does not affect the color of the stone (type Ia), but if nitrogen substitutes carbon in the crystal lattice, it causes a yellow color (Ib). Stones of type II may not contain impurities (IIa), or may contain boron substituting carbon, producing a blue color and semiconductivity of the diamond.
Diamonds form only at extremely high pressure (over 45,000 atmospheres) and temperatures over 1100°C (2012°F) from liquid ultrabasic magmas or peridotites. Diamonds, therefore, form at great depths in the earth's crust. They are delivered to the surface by explosive volcanic phenomena with rapid cooling rates, which preserve the diamonds from transformation. This process happens in kimberlites (a peridotitic type of breccia), which constitutes the infill of diamond-bearing pipes. Also found with diamonds are olivine, serpentine, carbonates, pyroxenes, pyrope garnet, magnetite, hematite, graphite and ilmenite. Near the surface, kimberlite weathers, producing yellow loose mass called yellow ground, while deeper in the earth, it changes to more dense blue ground. Diamonds are extremely resistive to corrosion, so they can be fond in a variety of secondary deposits where they arrived after several cycles of erosion and sedimentation (alluvial diamond deposits, for example). Even in diamond-bearing rock, the diamond concentration is one gram in 80 tons of rock.
Most diamonds are used for technical purposes due to their hardness. Gem quality diamonds are found in over 20 counties, mainly in Africa. The biggest diamond producer is South Africa, followed by Russia. Usually, diamonds appear as isolated octahedron crystals. Sometimes they may have rounded corners and slightly curved faces. Microcrystalline diamonds with irregular or globular appearance are called Bort (or boart), while carbonado are roughly octahedral, cubic or rhombic dodecahedral, blackish, irregular microcrystalline aggregates. Both are valued for industrial applications because they are not as brittle as diamond crystals. Frequently, diamonds have inclusions of olivine, sulfides, chrome-diopside, chrome-spinels, zircon, rutile, disthene, biotite, pyrope garnet and ilmenite. Transparent crystals are usually colorless, but sometimes may have various yellowish tints. Rarely, diamonds may be bright yellow, blue, pale green, pink, violet, and even reddish. Some diamonds are covered by translucent skin with a stronger color. Diamonds become green and radioactive after neutron irradiation, and yellow after further heating. They become blue after irradiation with fast electrons. Diamonds have different hardnesses along their different faces. Diamonds from different deposits also have different hardnesses. This quality allows for the polishing of faceted diamonds by diamond powder.
Most diamond gems are faceted into brilliant cuts. Due to the high reflective index, all light passing through the face of such facetted diamonds is reflected back from the back facets, so light is not passing through the stone. This can be used as a diagnostic property, because most simulants (except cubic zirconia) do not have this property. Diamonds do have many simulants, including zircon, corundum, phenakite, tour-maline, topaz, beryl, quartz, scheelite, sphalerite, and also synthetic gemstones such as cubic zirconia, Yttrium-aluminum garnet, strontium titanate, rutile, spinel, and litium nio-bate. Diamonds have high thermal conductivity, which allows it to be readily and positively distinguished from all simulated gemstones. The most expensive diamonds are those with perfect structure and absolutely colorless or slightly bluish-white color. Yellow tint reduces the price of the diamond significantly. Bright colored diamonds are extremely rare, and have exceptionally high prices.
See also Gemstones
Diamond (How Products are Made)
The diamond is the hardest natural substance known. It is found in a type of igneous rock known as kimberlite. The diamond itself is essentially a chain of carbon atoms that have crystallized. The stone's unique hardness is a result of the densely concentrated nature of the carbon chains. Like other igneous rocks, kimberlite was formed over the course of thousands of years by volcanic action that occurred during the formation of the earth's crust. Kimberlite is located inside these former spheres of volcanic activityften near mountain rangesn vertical shafts that extend deep inside the earth. Inside the kimberlite are intermittent deposits of diamonds, one of several minerals present. However, not all kimberlite contains diamond. Other stones often found with diamonds are mica, garnet, and zircon. Kimberlite may be blue-grey in huehus termed blue groundr if exposed to air it may have a yellowish cast and is called yellow ground.
It is thought that diamonds were first discovered in Indiaabout 6,000 years ago in the riverbeds of the region. Traders were responsible for bringing the gems as far east as China and as far west as Rome during the classical and early medieval eras. The Chinese were the first to hamess the unusually tough nature of the gem and used it as a tool to cut other stones. Pliny the Elder, a Roman scholar, wrote about the diamond in the first century. The word itself stems from the Greek term adamas which means "invincible" or "unconquerable."
From the earliest days, the diamond has been imbued with mystery and superstition. Because they were so raret first found only in Indiat became a commonly held superstition that the diamond lent its wearer special powers. They were worn in battle to insure victory and sometimes invoked as an antidote to poison. Other superstitions associated with the stone included the caveat that placing it in the mouth would bring on a loss of teeth. In other cases, finely ground diamond, made into a powder, was thought to be an effective poison. Indeed, experts agree that even in a pulverized form, the unique sharpness of the mineral would tear minuscule holes in the digestive tract. Because it is both the hardest and one of the rarest natural substances, diamonds have always fetched exceedingly high prices. The extreme value of the stone also made it a portable form of wealth in times of warfare and upheaval.
The actual mining of diamonds as an industry can be traced back to India to around 800 to 600 B.C. India was the only known source of the rocks for over a thousand years, until they were unearthed in Borneo around A.D. 600. During the Middle Ages, the diamond was overshadowed by some of the more colorful gems like the ruby and emerald. These other stones found their way into the jewelry of the rich and powerful of Europe more easily than the diamond. Additionally, gem-cutting techniques had not yet been developed to unleash the brilliance of the stone. Diamonds were usually left in their natural state or shaped by a rudimentary cut. In the 17th century, how-ever, a Venetian lapidary named Vincenzo Peruzzi developed the so-called brilliant cut. This cut revealed the intricacies and the natural perfection of the stone.
Image Pop-UpDiamond is found in a type of igneous rock known as kimberlite. Like other igneous rocks, kimberlite was formed over the course of thousands of years by volcanic action that occurred during the formation of the earth's crust. Inside the kimberlite are intermittent deposits of diamonds, one of several minerals present.
In the 18th century, diamond deposits were discovered in Brazil in small quantities, and later in Australia, Russia, and the United States. Brazilian gems were first taken to India and shipped to Europe as Indian diamonds, since people considered non-Indian gems less valuable. In the 20th century, an American mine near Murfreesboro, Arkansas, was open for novelty public mining for a small fee. High-quality diamonds have been found in Siberia, but the extremely cold temperature has made large-scale mining unfeasible.
In 1866 the world's largest cache of diamonds was discovered in South Africa. Some children had found a rock and brought it home, and a curious neighbor passed it on to a trader, who gave it to a geologist. It was discovered to be a diamond of enormous size and worth a small fortune. South Africa soon experienced a diamond rush, and shanty towns sprang up with the influx of prospectors. Eventually, the various mines and mine companies of the region were consolidated under the control of the DeBeers organization. With the DeBeers Consolidated Mines, Ltd., a Central Selling Organization, and a Diamond Trading Company, this conglomerate controls about 80% of the world's diamond output. Contemporary diamond mining is centered at Kimberley, South Africa, and carried out by DeBeers. Every six weeks or so, representatives of the DeBeers Diamond Trading Company invite a special list of diamond wholesalersess than a hundred world-wideo London to view preselected lots of the gem. This is the only method by which South African DeBeers diamonds come onto the market.
In modern times diamonds have become indispensable to industry. Automobile magnate Henry Ford was the first to uncover the contemporary industrial uses of the stone. He sponsored research into its applications for the manufacturing sector, especially as a low-cost abrasive, and the Detroit area became a hub for dealers of diamond tools. The aircraft industry followed the lead of the automotive sector, becoming an avid user of diamond-based products. Diamonds used for industrial applications are usually of a lower grade than those found in the gemstone market, but they retain the same properties of hardness and durability. Diamond
Tools made from industrial diamonds are used in the mirror and optical manufacturing fields as well as in gas and oil drilling endeavors. In the textile industry, devices made from diamonds are used to cut patterns. In medicine, cutting instruments made from diamonds are used to cleanly slice bone and tissue. The construction industry uses diamond tools in the grinding and cutting of concrete and pavement. Diamonds are also used to make needles for stereo record players.
Diamonds are chains of carbon. Carbon is one of the most common substances on the planet. In one form it is simple graphite, used in pencils, but in its crystallized form, it takes an altogether different appearance as diamond. On the scale used by mineralogists to measure the hardness of minerals, diamonds rate ten on a scale of one to ten. Diamonds are measured in carats, the standard unit of measurement for gemstones. One carat is roughly equal to one-fifth of a gram. The carat can be further divided into points based on a scale of 100. One of the reasons diamonds are so prized is because the light they absorb is reflected directly back outward, if the stone has been properly cut. The unusual crystal structure of the gem allows this high degree of refractability. Because of their structure, diamonds are also excellent conductors of electrical current.
Structurally, the diamond can be described as an octahedron. This means that there are double four-sided pyramids of carbon chains inside that meet one another at the bases. Cubes or dodacahedrons twelvesided shapere also found within the stone. Sometimes small triangular pockets called trigons can be observed.
Diamonds are found in nature in a variety of hues. Colorless or white diamonds are the most common, while some tinted stones are rare and valuable. The shades may be yellow, blue, pink, green, or amber. In South Africa it is common to see orange diamonds as jewelry, but this is a custom that has not made its way into the rest of the world. Some of the world's most famous diamonds are the colored oneshe heavy Dresden Green, for instance, and the infamous Hope Diamond. The latter, blue in color, is thought to hold certain negative energy, and many unexplained deaths have been associated with its owners. It is now in the collection of the Smithsonian Institution in Washington, DC.
Extraction and Refining
Diamonds are mined either from the kimberlite pipes below the earth's surface, or from alluvial deposits. Alluvial (riverbed) deposits occurred when volcanic action carried kimberlite and other minerals from the center of activity to naturally forming irrigation systems. Such diamonds are found quite near the earth's surface. In alluvial mining, considerable amounts of sand must first be removed from the area. The sand and other such components are called over-burden, and large mechanical scrapers are used to move it out of the way. Underneath the overburden lies a gravel bed, and bulldozers scoop the gravel up and set it aside in piles.
The piles are then taken to a screening plant, where the diamonds are extracted. In alluvial mining, it is sometimes necessary to reach the bedrock underneath the gravel bedr sometimes even below the bedrock itselfn order to unearth the diamond deposits. The bedrock must be thoroughly searched. Sometimes an enormous vacuum device called a Vacuveyer is used for this purpose. As the mining process moves along in a horizontal fashion, the removed overburden is again deposited to fill over the excavated sites.
Below-ground mining of kimberlite for diamond also requires moving enormous quantities of rock and other material in order to unearth gems, but on a much larger scale than alluvial mining. For one part diamond uncovered, it is estimated that 15 to 30 million parts waste must be moved out of the way. Unlike mining endeavors for gold or other substances, engineers cannot determine beforehand whether an area has a large abundance of diamond.
- 1 Block caving is the most commonly used method in excavating diamonds from kimberlite deposits. This method offers the highest yield and thus is the most cost effective. First, a large vertical hole is excavated, typically 1,750 feet (533 m) in diameter. Levels are placed approximately every 40 feet (12 m). Along these levels are horizontal tunnels known as scraper drifts. In the drifts, there are small inclined coneshaped openings at intervals of every 11 feet (3 m) or so. These openings are roughly four feet by four feet. When a horizontal slice is cut above the conessually about six feet (1.8 m) in heighthe kimberlite begins to break off and fall into the cone and into the scraper drift. The material is then pushed onto trucks. The trucks travel underground through the mining area and take the collected kimberlite to a crushing device.
- 2 In the crushing operation, which occurs in the below-ground mining facilities, large chunks of kimberlite are broken up into more easily transportable segments. After an initial crushing, the kimberlite passes through a grizzly, or a set of iron bars. If the crushed chunks do not pass through the grizzly, they are still too large, and they are sent back for further crushing. The crushed kimberlite is then taken above the surface for further processing. When no more kimberlite is found entering the cones, the area is depleted and work moves on to a lower level.
- 3 The actual diamonds must be separated from the rock that surrounds them. Crushing or milling the excavated material is the first step, but this is done in a rudimentary form so as not to damage the potential gems inside. Next, a gravity-based device is used to sort the diamond-containing portionsalled the concentraterom the tailings, or the filler rock. One of the most commonly used methods to separate the two is a type of washing pan developed in South Africa in the 1870s. Decomposed kimberlite and watern a mixture known as a puddles put into the pan. The mixture's viscosity is a crucial element, because the lighter particles will rise to the top, but the diamonds and other heavy minerals will descend to the bottom of the pan.
Another method of uncovering diamonds uses media separators. A stew called a slurry is made upypically consisting of water added to the crushed concentrate and tailings. Ferro-silicon powder, which has a heavy density, is also added.
The slurry may be put into one of three types of media separators. The first is a cone-shaped tank, with a cone-shaped agitating element inside. The agitator moves around the sides of the tank, but leaves enough room so that the lighter tailings can rise to the top and the heavier elements sink to the bottom. In a lifting-wheel type of media separator, a wheel is filled halfway with slurry. Paddles inside it agitate the mixture, and lift the heavy particles from the bottom and separate them from the rest of the mixture. The third type of media separator is known as a hydrocyclone. It is a large vat that spins around, and through centrifugal force, the heavier, diamond-rich particles are separated.
- 4 After this rudimentary separation, the concentrate moves to a greasing area, another innovation in diamond manufacturing developed in South Africa in the late 19th century. Mixed with water, the kimberlite-and-diamond mixture is placed on a greased belt or table. This device is usually slanted and vibrated. The method operates on the premise that diamonds newly excavated will not become wet when brought into contact with water. Instead they will stick to the grease. Petroleum jelly is usually the preferred substance on the grease belt or table. The water then carries away the remaining non-diamond particles. The diamond-laden concentrate is then swept off the table and boiled to remove the traces of grease. In a newer method, X-ray technology is used to determine which of the concentrate is diamond and which is effluvial material.
- 5 Chunks of diamond eventually become small, perfectly shaped gemstones commonly used in engagement rings and other jewelry. Since diamond is the hardest known substance, diamond dust must be used to cut the stone. In cutting, a minuscule groove is incised into the surface of the diamond, and a cleaving iron is inserted into the groove. With a quick, forceful blow, the diamond should split perfectly along its naturally occurring planes. The lapidary determines further cuts by marking them off on the surface with ink. Next, a diamond saw, oiled with the unusual combination of diamond dust and olive oil, is rotated vertically on the surface of the raw gem. This device divides the diamond into new segments. These parts are then fed into a lathe-like device for grinding.
Diamonds are a finite resource. The fate of Indian diamonds is a good example of what the future might hold for the South African diamond-mining industry. From the first discovery of the gems in India until relatively recently, it is thought that over 12 million carats originated from India. By the mid-20th century, the resources were nearly depleted, and India was producing only about 100 carats annually. Diamonds will continue to be used in industry and high-technology enterprises, but synthetically produced facsimilesirst manufactured in 1953ay accomplish some of the tasks originally the exclusive province of the real stone. These "manufactured" gems have the same properties of hardness and durability, and while they will never be as popular as the real diamond for adomment purposes, they are well suited for industrial applications.
Where To Learn More
Arem, Joel A. Gems and Jewelry, 2nd ed. Geoscience Press, 1992.
Austin, Gordon T. "Diamond." American Ceramic Society Bulletin, May 1990, p. 854-55.
"More Australian Diamonds?" Engineering and Mining Journal, November 1992, p. 62.
"Diamond Explorationhe Trace Element Revolution." Engineering and Mining Journal, July 1994, p. 7.
Galli, Giulia, Richard M. Martin, and Roberto Car. "Melting of Diamond at High Pressure." Science, December 14, 1990, p. 1547-49.