Diamond

Background

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 activity—often near mountain ranges—in 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 hue—thus termed blue ground —or if exposed to air it may have a yellowish cast and is called yellow ground.

History

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 rare—at first found only in India—it 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.

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 wholesalers—less than a hundred world-wide—to London to view preselected lots of the gem. This is the only method by which South African DeBeers diamonds come onto the market.

Industrical Applications

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 last much longer than those made from other sources and offer a nearly unmatched precision in cutting other substances. Additionally, such tools work faster and much more quietly than other alternatives.

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.

Physical Characteristics

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—a twelvesided shape—are 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 ones—the 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 bed—or sometimes even below the bedrock itself—in 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.

Mining

• 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 cones—usually about six feet (1.8 m) in height—the 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.

Crushing

• 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.

Separating

• 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 portions—called the concentrate—from 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 water—in a mixture known as a puddle—is 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 up—typically 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.

Greasing

• 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.

Cutting

• 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.

The Future

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 facsimiles—first manufactured in 1953—may 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

Book

Arem, Joel A. Gems and Jewelry, 2nd ed. Geoscience Press, 1992.

Periodicals

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 Exploration—The 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.

—Carol Brennan

DIAMOND

DIAMOND . The diamond, first of all, participates in the hierophany of stones signifying in religious consciousness that which is hard, rugged, and unchanging. Above all, stone is. Like all precious stones, the diamond also partakes of the general symbolism of treasures and riches, which in religious terms represent moral and intellectual knowledge.

As a symbol the diamond, as the hardest of all stones, has a wide range of meanings, among them indestructibility, constancy, the unyielding, and dominance. Because of its brilliance it also signifies unconquerable light, excellence, frankness, joy, life, and purity.

In Greek the word for "diamond" is derived from adamas, meaning "invincible, unconquerable." In some places, and especially on Greek emblems, it indicated the irradiant mystic center, a meaning discovered in the most obscure examples as well as in the most prominent. Jean Chevalier and Alain Gheerbrant (1982) point out that the German word Eckstein ("cornerstone") also refers to the diamond in a deck of cards. The cornerstone is one of many symbols for the center. In a more obvious example, Plato likens the axis of the world to a diamond.

Until the nineteenth century, diamonds were found almost entirely in India. On the subcontinent the word vajra meant both "lightning" and "diamond." Thus, the vajra of the god Śiva has a double aspect as thunderbolt and diamond scepter. Vajra also belongs to the god Agni as a spiritual power and to Indra as a temporal power. As a diamond vajra is adamantine and depicts spiritual power, but as thunderbolt and lightning it also represents both destruction and fertilization, death-dealing and life-giving powers, the alternating and complementary forces of the universe.

The symbol of the vajra is important in Buddhism as well, where it symbolizes the power of the Buddha's teaching (the dharma ) to overcome the deluding passions of sentient beings. The Diamond Throne or Seat is the place of enlightenment. Situated at the foot of the bodhi tree, it is the unchangeable axis or center of the world.

In Tantric Buddhism vajra represents immutable, unalterable spiritual power. Symbolizing clarity and light, it also refers to the indeterminate character and ultimate emptiness of the Buddha nature. Mircea Eliade cites a Tantric text that makes a clear identification between śūnyatā ("voidness") and vajra. The Chan patriarch Huineng is said to have declared that neither that which is waxing nor that which is waning is the diamond.

In the traditional mineralogy of the Indian subcontinent, the diamond represents perfection. Stones and metals were thought to grow within the earth's womb, each with its own lethargic pace and rhythm. The crystal was unripe (Hindi, kacchā) and constituted a state of intermediate maturation. The diamond was the epitome of maturity and ripeness (Hindi, pakkā). The crystal is not hard; the diamond is. The Indian alchemist, associating the diamond with immortality, identified it with the philosophers' stone.

Similarly, in Tibetan iconography the diamond scepter signifies the adamantine or immutable world, which is also potential or nonmanifest. The bell or tilpa refers to the phenomenal world, which is manifest and changing. The diamond scepter is the active principle; the bell is the passive. The former is wisdom and the latter, human reason.

The diamond has also been linked with the supreme female divinity, who is usually associated with the earth. In Tibet the earth goddess Tārā has a human incarnation, the Diamond Sow. She is also traditionally regarded as the consort of or feminine counterpart to the bodhisattva Avalokiteśvara. In the transition from tarot cards to modern playing cards, diamonds replaced the ancient suit of pentacles, which had been symbols of Mother Earth (Tārā) and of the earth as feminine.

The characteristics of hardness and durability have lent themselves to other meanings. In the Old Testament the diamond could symbolize hardness of the heart and forehead (Jer. 17:1). In Rome it was believed that the stone promoted harmony, and that it guarded health and vitality if worn on the left hand, close to the heart. This belief probably informed its character as an emblem of reconciliation in the Middle Ages and as a sign of betrothal in the modern world.

In some places the diamond's brilliance and lucidity made it a symbol for Christ. In Hebrew culture the sixth stone of the high priest's breastplate, a diamond, was said to become dark or light according to the guilt or innocence of an accused person.

Mircea Eliade (1958) has related diamonds to "snake stones," which in many cultures are thought to have fallen from the heads of snakes or dragons. In ancient India, and later in the Hellenistic and Arab worlds, it was believed that the stones were poisonous if anyone touched them with their lips, because they had once been in a snake's throat. The notion that precious stones came from snake spittle has been found in areas ranging from China to Great Britain.

Pliny the Elder (23–79 ce) described the dracontia, or dracontites, that were to be found in the brains of dragons. Philostratus the Lemnian (b. c. 190 ce) reported that the eyes of some dragons were stones of blinding brilliance imbued with magical powers. Sorcerers, he relates, after they have worshiped reptiles, cut off their heads and take out the precious stones.

Given such beliefs, it is not surprising that the diamond has a reputation as a remedy for snakebite. Indeed, Pliny describes it as a universal talisman, rendering poisons and every malady harmless and causing evil spirits and bad dreams to depart. In occidental Europe, the diamond has been thought to chase away savage beasts, phantoms, sorcerers, and the terrors of the night. In Russia, its purity and lucidity have made it a charm to impede lust and to strengthen the resolve of the chaste.

Bibliography

Jean Chevalier and Alain Gheerbrant, in Dictionnaire des symboles (Paris, 1982), have written an interesting and often provocative essay on the diamond. Mircea Eliade, in Patterns in Comparative Religion (New York, 1958), primarily discussed the diamond as a magical object. His description of the significance of the stones in the same book is also helpful. Berthold Laufer's book The Diamond: A Study in Chinese and Hellenistic Folklore (Chicago, 1915), is one of the few sources that include substantial material on the diamond as a symbol rather than a physical object.

New Sources

Harlow, George, ed. The Nature of Diamonds. New York, 1997.

Hart, Matthew. Diamond: A Journey to the Heart of an Obsession. New York, 2001.

Kendall, Leo P. Diamonds Famous and Fatal: The History, Mystery and Lore of the World's Most Famous Gem. Fort Lee, N.J., 2001.

Elaine Magalis (1987)

Revised Bibliography

Diamond

Resources

A diamond is a precious stone (mineral) that is considered a clear and generally colorless crystalline form of pure carbon, with the same carbon composition as graphite, but with a different structure. It is the hardest of naturally occurring substances. Diamonds are usually found in igneous rock formations and alluvial deposits. Most diamonds are billions of years old. They are often used in industrial and scientific applications. The density of diamond is about 2.0 ounces per cubic inch (3.5 grams per cubic centimeter).

Diamonds, of course, are used as jewelry, especially in engagement and wedding rings. Natural and synthetic diamonds are also commonly used to cut a wide variety of materials. Manufacturers, medical surgeons, and many other groups and organizations use diamond knives, drills, saws, and other diamond-cutting devices to cut and shape their products and materials. Makers of marble, granite, and other natural stone products use diamond blades to cut, grind, and polish their unfinished products.

The word diamond comes from the Greek word adamas, meaning invincible. Diamonds were first found (it is believed) in the sands of India. Alexander the Great (356–323 BC) introduced them to Europe in 327 BC.

French chemist Antoine Laurent Lavoisier (1743– 1794) showed in the eighteenth century that, when air is present, diamonds are combustible, producing carbon dioxide. English chemist Sir Humphrey Davy (1778–1829) demonstrated in 1814 that the sole product of the combustion of diamonds in oxygen is carbon dioxide. He also proved that diamond and charcoal both consist of carbon atoms, so they are chemically identical. This was the first demonstration that two materials with the same chemical composition need not have the same physical properties.

Most people probably believe that diamonds only come from South Africa. However, diamonds are found around the world, except for the continents of Europe and Antarctica. Before the twentieth century, only a few diamond deposits were known. Between the fourth century BC and the sixth century AD, India was the only source of diamonds. Diamonds virtually disappeared from Europe for about one thousand years during the Middle Ages. In 1725, diamonds were discovered in Brazil. Then, in the 1870s, they were also found in South Africa. By this time, the supply of diamonds increased dramatically as the worldwide demand for diamonds also increased.

Today, diamonds are mined in about 25 countries. According to the American Museum of Natural History, as of 2005, about 130 million carats of diamonds are mined annually throughout the world.

Diamonds are a globally traded commodity used for a variety of industrial and artistic purposes. In December 2000, the United Nations General Assembly unanimously adopted a resolution articulating the role of diamonds in fuelling international conflict and dedicated to breaking the link between the illicit transaction of rough diamonds and armed conflict. Two years later, in 2002, the UN approved the Kimberley Process, which further attempts to prevent conflicts in the diamond market. In 2003, U.S. President George W. Bush enacted an executive order imposed trade sanctions against Sierra Leone due to human rights violations with respect to its diamond trade with the United States. These conflict diamonds are facing increasing import-export trade restrictions. Overall, however, the U.S. Government Accountability Office stated in September 2006 that despite sanctions and enforcement conflict diamonds continue to illegally come into the United States in large numbers.

The atoms making up a mineral may be arranged either randomly, or in an orderly pattern, if —as with diamonds—a mineral’s atoms show long-range organization, the mineral is termed a crystalline mineral. The objects commonly called crystals are crystalline minerals of relatively large size that happen to have developed smooth faces. Diamonds are 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 0.001–0.23% 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 45000 atmospheres) and temperatures over 2012°F (1100°C) 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 Earth, it changes to more dense blue ground. Diamonds are extremely resistive to corrosion, so they can be found 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 g in 8 to 30 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, phena-kite, tourmaline, topaz, beryl, quartz, scheelite, sphalerite, and also synthetic gemstones such as cubic zirconia, yttrium-aluminum garnet, strontium titanate, rutile, spinel, and litium niobate. 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.

In January 2003, a number of international concerns came to a preliminary consensus on the Kimberley Process Certification Scheme to curtail international trade in what are termed conflict diamonds.

As of early 2003, nearly 50 countries agreed to use and require standardized, tamper-proof packaging and official certificates attesting to the source of the enclosed diamonds when shipping rough uncut diamonds. Such controls are designed to stem illegal trade in diamonds and to reduce the ability of despotic regimes to exploit diamond trade to perpetuate their political and or military power (e.g., the protocols prohibit trade in contraband diamonds from rebel sources in Sierra Leone). Without proper certification, many nations and industrial sources have agreed not to import or purchase diamonds.

See also Mineralogy.

Resources

BOOKS

Hart, Matthew. Diamond: A Journey to the Heart of an Obsession. New York: Walker & Co., 2001.

Klein, Cornelis. Manual of Mineral Science, 22nd ed. New York: John Wiley & Sons, 2001.

O’Donaghue, Michael, ed. Gems: Their Sources, Descriptions, and Identification. Oxford, UK, and Burlington, MA: Butterworth-Heinemann, 2006.

Paterson, Vicky. Diamonds. Richmond Hill, Ontario, Canada: Firefly Books, 2005.

Yavor Shopov

David Diamond

Composer, educator

The American composer and teacher David Diamond wrote in a wide variety of styles and in virtually every medium. The strength of his music lay in its imposing formal design and its serious expression, although it also embodied lyrical warmth and romanticism. Diamond was one of a group of composers who forged a distinctly American idiom of classical music in the middle of the twentieth century. He lived long enough to see his music fall out of favor due to the influence of the European-devised 12-tone system, and then to witness its revival during the more eclectic scene at the end of the twentieth century.

David Diamond was born on July 9, 1915, in Rochester, New York. He was the son of Austrian-Polish Jewish immigrants who could not afford to cultivate the musical aptitude that their son showed from about the age of six. Fortunately, the young boy's abilities also impressed others who were in a better position to help him. At a public school in Rochester, he received a violin and free lessons, and in 1927, when the family moved to Cleveland, André de Ribaupierre taught him violin and theory without remuneration at the Cleveland Institute of Music.

Upon returning to Rochester in 1929, Diamond entered the preparatory department of the Eastman School of Music on a scholarship, studying violin with Effie Knauss and composition with Bernard Rogers. He continued at Eastman as an undergraduate after finishing high school in 1933, but left after one year to move to New York. Again on a scholarship, he studied the Dalcroze method of Eurhythmics with Paul Boepple and composition with Roger Sessions at the New School from 1934 to 1936, and continued privately with Sessions until 1937.

Diamond made three trips to Paris in the mid-to-late 1930s (the last through funds from the first of three Guggenheim Fellowships), where he studied with the famous French teacher Nadia Boulanger and met many of the great artists then living in Paris, such as Albert Roussel, Igor Stravinsky, Maurice Ravel, André Gide, and Charles Munch. Important compositions from these Paris years include the first of his three violin concertos (1936, 1947, and 1967); Psalm for orchestra (1936), his first work to receive wide attention and also the Juilliard Publication Award in 1938; a cello concerto (1938); and Heroic Piece (1938) for small orchestra. He applied for a job teaching at Columbia University in 1938 but was turned down, and he recalled to Chris Pasles of the Los Angeles Times that he was told he should "stop wearing turtleneck sweaters," which he believed was an indication that he should keep his homosexuality in the closet.

Germany's declaration of war on France in 1939 brought Diamond back to the United States for most of the next 12 years. At first he had to scramble financially, working the night shift at a soda counter and then landing a spot as violinist in the orchestra of the weekly Hit Parade radio show. During this time he composed both chamber and orchestral works, and their performance attracted financial support from foundations and other funders. Among his chamber works of the period are the first three of his eleven string quartets; a piano quartet for which he won the Paderewsky Prize (1938); a concerto for two solo pianos (1942); a sonata for piano (1947); and a Chaconne for violin and piano (1948). Orchestral works of the period include the first four of his eight symphonies; The Dream of Audubon, a ballet (1941); music for Shakespeare's The Tempest for orchestra (1944); Rounds for string orchestra (1944); music for Shakespeare's Romeo and Juliet for orchestra (1947); and a piano concerto (1950).

Diamond lectured on American music in Salzburg during the summer of 1949, and two years later went to Italy on a Fulbright Fellowship. His motivations for leaving were complex. Diamond's brand of accessible orchestral music was being temporarily eclipsed by the difficult, rigorously intellectual 12-tone method. He also pointed to anti-Semitism and resistance to his open homosexuality as reasons for a decline in the performance of his works in the United States, and he was dismayed by a subpoena to appear before the U.S. House of Un-American Activities Committee. He stayed in Italy, first in Rome and then in Florence, for 14 years, returning to the United States on two occasions (1961 and 1963) to teach at the State University of New York at Buffalo as Slee Professor of Music. The years in Italy proved musically productive for Diamond, who composed works including The Midnight Meditation, a cycle for voice and piano (1951); a piano trio (1951); string quartets 4-8; symphonies 5-8; sonatas for solo violin (1954) and for cello (1956); Sinfonia Concertante (1954–1956); The World of Paul Klee for orchestra (1957); a woodwind quintet (1958); The Sacred Ground for baritone, chorus, children's chorus, and orchestra (1962); and Elegies for flute, English horn, and strings (1963).

Returning to the United States in 1965, Diamond became chair of the composition department at the Manhattan School of Music; he resigned in 1967. A position as composer-in-residence at the American Academy of Rome drew him back to Italy during 1971 and 1972. After 1973 he was professor of composition at the Juilliard School of Music in New York. Some of his better-known compositions from the years 1964 to 1984 were We Two (1964), Hebrew Melodies (1967), and The Fall (cycles for voice and piano, 1970); Music for Chamber Orchestra (1969); The Noblest Game, (an opera, 1971–1975); a piano quintet (1972); and Ode to the Morning of Christ's Nativity for a cappella chorus (1980).

Several writers have suggested that the early 1950s marked a rather abrupt change to a dissonant and nontonal style, some even stating that Diamond had taken up the 12-tone method. Diamond himself refuted this last statement in an article appearing in the New York Times, saying, "I am not now and never have been a 12-tone composer." He even commented to Matt Schudel of the Washington Post: "I hated all that avant-garde stuff. It was all wrong. They don't write out of love." While his music became gradually less tonal in later years, he always commanded a variety of styles, which he used according to the function of the music. The music for Broadway productions of Shakespeare plays, for instance, was quite lush and tonal, while the more absolute works, such as the fourth symphony, frequently involved a more complicated language (here polytonality). As the grip of the 12-tone system over American compositional life began to loosen, Diamond's works enjoyed a revival in popularity. He was championed by conductors such as Leonard Bernstein and by Seattle Symphony music director Gerard Schwarz.

The 1980s and 1990s saw works such as the ninth symphony in a series that Diamond had begun nearly 45 years earlier. The symphonies were introduced steadily from 1940 until 1965, but it was not until 1985 that Diamond finally unveiled the ninth. In 1996, the Juilliard Orchestra performed the world premiere of Diamond's Concerto For String Quartet and Orchestra, which the Juilliard School commissioned from Diamond in honor of the 50th anniversary of the Juilliard Quartet. The performance met high praise, notably from the Village Voice's Leighton Kerner, who wrote, "American music boasts no composer more brilliant or more melodically imaginative, and this new concerto bears out the fact." Even at 81 years of age, Diamond seemed to have boundless reservoirs of creativity and energy.

Modern rhythmic complexities energized his later compositions such as Warning for chorus and tubular bells (1973). While thus embracing some of the innovations of the twentieth century, Diamond rejected others, most emphatically the aleatoric or chance music of John Cage and his followers. Reflecting on his career, Diamond commented, "One hopes the future will bring my music to a larger audience, one not interested in Trends and The Now, but music for All Time, for all humanity." He remained active into old age, completing his Symphony No. 11 in 1991 in response to a commission from the New York Philharmonic Orchestra on the occasion of its 150th anniversary. Diamond died in Rochester on June 13, 2005.

For the Record …

Born on July 9, 1915, in Rochester, NY; died on June 13, 2005, in Rochester, NY. Education: Attended Cleveland Institute of Music; Eastman School of Music; New School, New York City; studied composition privately with Roger Sessions and with Nadia Boulanger.

Worked night shift at soda counter, New York, 1939; played violin in Hit Parade radio orchestra, early 1940s; works widely performed by American symphony orchestras, 1940s; moved to Rome, 1951; taught at Rome University, early 1950s; lived in Florence, Italy, early 1950s–1965; taught at University of Buffalo, 1961, 1963; returned to U.S., taught at Manhattan School of Music, 1965–67; professor of composition, Julliard School, New York City, 1973–86.

Awards: Guggenheim Fellowship, 1938 (renewed, 1940s); New York Music Critics' Circle Award, for String Quartet No. 3, 1947; William Schuman Lifetime Achievement Award, 1986; American Academy of Arts and Letters, gold medal, 1991; National Medal of the Arts, 1995.

Selected works

Sinfonietta (for orchestra), 1935.
TOM, ballet, 1936.
Elegy in Memory of Ravel, for strings and percussion, 1937.
Psalm for Orchestra, 1937.
Elegy in Memory of Maurice Ravel, 1937.
Symphony No. 1, 1941.
Concerto for Two Solo Pianos, 1942.

String Quartet No. 2, 1943.
Symphony No. 2, 1943.
Rounds (for string orchestra), 1944.
Symphony No. 3, 1945.
String Quartet No. 3, 1946.
Sonata for Piano, 1947.
Chaconne for Violin and Piano, 1948.
String Quartet No. 4, 1951.
Symphony No. 5, 1965.
String Quartet No. 8, 1965.
To Music (for orchestra and chorus), 1967.
The Noblest Game (opera), 1975.
Symphony No. 11, 1991.

Sources

Books

Contemporary Composers, St. James, 1992.

Ewen, David, American Composers: A Biographical Dictionary, 1982.

Kimberling, Victoria, David Diamond: A Bio-Bibliography, Scarecrow, 1987.

Periodicals

Daily Telegraph (London, England), June 25, 2005.

Los Angeles Times, June 16, 2005, p. B11.

Music Journal, April 1964.

New York Times, April 22, 1965; June 15, 2005, p. C20.

South Florida Sun-Sentinel, June 24, 2005.

Times (London, England), July 1, 2005, p. 70.

Village Voice, October 22, 1996.

Washington Post, June 16, 2005, p. B6.

Online

"David Diamond," Peer Music Classical, http://www.peermusicclassical.com/composer/Diamond.cfm (March 10, 2006).

Diamond

Diamond is a mineral with the same carbon composition as graphite, but with different structure.

Diamonds are a globally traded commodity used for a variety of industrial and artistic purposes. In December 2000, the United Nations General Assembly unanimously adopted a resolution articulating the role of diamonds in fuelling international conflict and dedicated to breaking the link between the illicit transaction of rough diamonds and armed conflict. These "conflict diamonds" are facing increasing import-export trade restrictions.

The atoms making up a mineral may be arranged either randomly, or in an orderly pattern, if—as with diamonds—a mineral's atoms show long-range organization, the mineral is termed a crystalline mineral. The objects commonly called crystals are crystalline minerals of relatively large size that happen to have developed smooth faces. Diamonds are 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 0.001–0.23% 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 45000 atmospheres) and temperatures over 2012°F (1100°C) 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 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 1 g in 8–30 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, tourmaline, topaz, beryl, quartz, scheelite, sphalerite, and also synthetic gemstones such as cubic zirconia, Yttrium-aluminum garnet, strontium titanate, rutile, spinel, and litium niobate. 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.

In January 2003, a number of international concerns came to a preliminary consensus on the Kimberley Process Certification Scheme to curtail international trade in what are termed conflict diamonds.

As of early 2003, nearly 50 countries agreed to use and require standardized, tamper-proof packaging and official certificates attesting to the source of the enclosed diamonds when shipping rough uncut diamonds. Such controls are designed to stem illegal trade in diamonds and to reduce the ability of despotic regimes to exploit diamond trade to perpetuate their political and or military power (e.g., the protocols prohibit trade in contraband diamonds from rebel sources in Sierra Leone). Without proper certification many nations and industrial sources are agreed to import or purchase contraband diamonds.

See also Mineralogy.

Yavor Shopov

Resources

books

Hart, Matthew. Diamond: A Journey to the Heart of an Obsession. New York: Walker & Co., 2001.

Klein, Cornelis. Manual of Mineral Science. 22nd. ed. New York: John Wiley & Sons, 2001.

Schumann, Walter. Gemstones of the World. London: Sterling Publications, 2000.