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Alternate meanings: Diamond (disambiguation)

Diamond is one of the natural allotropes of carbon (the most familiar allotrope being graphite; see also allotropes of carbon). The of all naturally occurring materials, diamonds cut into multi-faceted shapes are among the most prized gemstones of jewelry and find use in industrial applications as well.

Material properties

Main article: Material properties of diamond

Diamond is a transparent crystal of pure carbon consisting of tetrahedrally bonded carbon atoms. Humans have been able to adapt diamonds for many uses because of the material's exceptional physical characteristics. Most notable among these properties are the extreme hardness of diamond and its high dispersion index. These two properties form the basis for most modern applications of diamond.

Mechanical properties

Crystal structure: Diamonds typically crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms. A rare second form called lonsdaleite has hexagonal symmetry. The tetrahedral arrangement of atoms in a diamond crystal is the source of many of diamond's properties; graphite, another allotrope of carbon, has a rhombohedral crystal structure and as a result shows dramatically different physical characteristics.

Hardness: Diamond is the hardest known naturally occurring material, scoring 10 on the relative Mohs scale of mineral hardness and having an absolute hardness value of between 167 and 231 gigapascals in various tests. Diamond's hardness has been known since antiquity, and is the source of its name. The diamond derives its name from the Greek adamas, meaning "untameable" or "unconquerable", referring to its hardness.

Broad industrial applications of diamond are based on the extraordinary hardness of diamond. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial adaptations of this ability include diamond-tipped drill bits and saws.

The hardness of diamonds also contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well, keeping its luster over long periods of time. Unlike many other gems, it is well-suited to daily wear due to its resistance to scratching — perhaps contributing to its popularity as the preferred gem in an engagement ring or wedding ring, which are often worn every day.

Toughness: Unlike hardness, which only denotes resistance to scratching, diamond's toughness is only fair to good. Toughness relates to a material's ability to resist breakage from forceful impact. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamonds cut into certain particular shapes are therefore more prone to breakage than others.

Color: Diamonds occur in a variety of transparent hues — colorless, white, steel, blue, yellow, orange, red, green, pink, brown — or colored black. Diamonds with a detectable hue to them are known as colored diamonds. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly-pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal lattice. The most common impurity, nitrogen, causes a yellowish or brownish tinge.

Thermodynamic stability: At surface air pressure (one atmosphere), diamonds are not as stable as graphite, and so the decay of diamond is thermodynamically favorable (δH = −2 kJ / mol). Diamonds have been shown to burn in the late 18th century, and previously during Roman times. So, despite the popular advertising slogan, diamonds are definitely not forever. However, owing to a very large kinetic energy barrier, diamonds are metastable; they will not decay into graphite under normal conditions.

Electromagnetic properties

Optical properties: Diamonds exhibit a high dispersion of visible light. This strong ability to split white light into its component colors is an important aspect of diamond's attraction as a gemstone, giving it impressive prismatic action that results in so-called fire in a well-cut stone. The luster of a diamond, a characterization of how light interacts with the surface of a crystal, is brilliant and is described as adamantine, which simply means diamond-like. Some diamonds exhibit fluorescence of various colors under long wave ultraviolet light, but generally show bluish-white, yellowish or greenish fluorescence under X-rays. Some diamonds show no fluorescence.

Electrical properties: Except for most natural blue diamonds which are semiconductors, diamond is a good electrical insulator. Blue diamonds owe their semiconductive property to boron impurities, which act as a doping agent and cause p-type semiconductor behavior. Natural blue diamonds which are not boron-doped, such as those recently recovered from the Argyle mine in Australia that owe their color to an overabundance of hydrogen atoms, are not semiconductors.

Thermal properties: Unlike most electrical insulators, diamond is a good conductor of heat because of the strong covalent bonding within the crystal. Most natural blue diamonds contain boron atoms which replace carbon atoms in the crystal matrix, and also have high thermal conductance. Specially purified synthetic diamond has the highest thermal conductivity (2000–2500 W/(m·K), five times more than copper) of any known solid at room temperature. Because diamond has such high thermal conductance it is already used in semiconductor manufacture to prevent silicon and other semiconducting materials from overheating.

Gemological characteristics

The use of diamonds as gemstones of decorative value is the most familiar use to most people today, and is also the earliest use, with decorative use of diamonds stretching back into antiquity. Over time, especially since around 1900, experts in the field of gemology have developed methods of characterizing diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, clarity, color, and cut.

Most gem diamonds are traded on the wholesale market based on single values for each of the four Cs; for example knowing that a diamond is rated as 1.5 carats, VS2 clarity, F color, excellent cut, is enough to reasonably establish an expected price range. More detailed information from within each characteristic can then be used to determine actual market value for individual stones. Consumers who purchase individual diamonds are often advised to use the four Cs to pick the diamond that is "right" for them; to these is sometimes added the "fifth C" of cost.

Other characteristics not described by the four Cs can and do influence the value of a gem diamond. The effect of these secondary characteristics on the beauty and market value of a diamond is generally less than those of the four Cs. These characteristics include physical characteristics such as the presence of fluorescence, as well as data on a diamond's history including its source and which gemological institute performed evaluation services on the diamond.

Carat

The carat weight (actually mass) of a diamond measures the mass of a diamond. One carat is defined as exactly 200 milligrams (about 0.007 ounce). All else being equal, the value of a diamond increases exponentially in relation to carat size. Larger diamonds are both rarer and more desirable for use as gemstones. A review of comparable diamonds available for purchase in March 2005 demonstrates this effect (approximate prices for round cut, G color, VS2 diamonds with "1A" cut grade, as listed on http://www.pricescope.com):

The price per carat does not increase smoothly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less. As an example, a 0.95 carat diamond has a significantly lower price per carat than a comparable 1.05 carat diamond, due to differences in demand.

In the wholesale trade of gem diamonds, carat is often used in denominating lots of diamonds for sale. For example, a buyer may place an order for 100 carats of 0.5 carat, D–F, VS2-SI1, excellent cut diamonds, indicating he wishes to purchase 200 diamonds (100 carats total mass) of those approximate characteristics. Because of this, diamond prices (particularly among wholesalers and other industry professionals) are often quoted per carat, rather than per stone.

Total carat weight (t.c.w.) is a phrase used to describe the total mass of diamonds or other gemstone in a piece of jewelry, when more than one gemstone is used. Diamond earrings, for example, are usually quoted in t.c.w. when placed for sale, indicating the mass of both diamonds together and not each individual diamond.

Clarity

Main article: Diamond clarity

Clarity is a measure of internal defects of a diamond called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. The Gemological Institute of America (GIA) and others have developed systems to grade clarity, and are generally based on those inclusions which are visible to a trained professional when a diamond is viewed from above under 10x magnification.

Diamonds become increasingly rare when considering higher clarity gradings. Only about 20 percent of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80 percent are relegated to industrial use. Of that top 20 percent, a significant portion contains an inclusion or inclusions that are visible to the naked eye upon close inspection. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers, although visible inclusions can sometimes be hidden under the setting in a piece of jewelry.

Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. However, large clouds can affect a diamond's ability to transmit and scatter light. Large cracks close to or breaking the surface may reduce a diamond's resistance to fracture.

Color

Main article: Diamond color

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white diamonds are discounted in price as more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable.

Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration due to his effect undetectable. The GIA has developed a rating system for color in white diamonds, from "D" to "Z" (with D being "colorless" and Z having a clear light yellow or brown coloration), which has been widely adopted in the industry and is universally recognized. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades. While the prices are higher for colorless diamonds, the exact color most valued by a consumer is a matter of personal preference, with some preferring the very transparent D–F range, while others prefer the "warmer" colors in the G–J range and still others prefer a clearly visible tint.

In contrast to yellow or brown hues, diamonds of other colors are much rarer and more valuable. While even a pale pink or blue hue may increase the value of a diamond, more intense coloration is usually considered more desirable and commands the highest prices. A variety of impurities and structural imperfections cause different colors in diamonds, including yellow, pink, blue, red, green, brown, and other hues. Diamonds with unusual or intense coloration are sometimes labeled "fancy" by the diamond industry. Intense yellow coloration is considered one of the fancy colors, and is separate from the color grades of white diamonds. Gemologists have developed rating systems for fancy colored diamonds, but they are not in common use due to the relative rarity of colored diamonds.

Cut

Main article: Diamond cut

The cut of a diamond describes the manner in which a diamond has been shaped and polished from its beginning form as a rough stone to its final gem proportions. The cut of a diamond describes both the shape a diamond is formed into, as well as the quality of worksmanship. Diamond cutting is the art and science of creating a gem-quality diamond out of mined rough.

Shape

Diamonds do not show their beauty as rough stones; instead, they must be cut and polished to release the characteristic fire and brilliance that diamond gemstones are known for. Diamonds are cut into a variety of shapes that are generally designed to accentuate these features. The techniques for shaping diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky. He developed the round brilliant cut by calculating the ideal shape to return and scatter light when a diamond is viewed from above. The modern round brilliant has 57 facets (polished faces), counting 33 on the crown (the top half above the middle or girdle of the stone), and 24 on the pavilion (the lower half below the girdle). More information about the facet count is in the Diamond cut article.

Diamonds which are not cut to the specifications of Tolkwosky's round brilliant shape are known as fancy cuts. Popular fancy cuts include the baguette (from the French, resembling a loaf of bread), marquise (resembling the shape of a playing-card diamond), princess (square outline), heart, briolette (a form of the rose cut), and pear cuts. Generally speaking, these "fancy cuts" are not held to the same strict standards as Tolkowsky-derived round brilliants. Cuts are influenced heavily by fashion; baguettes—which accentuate a diamond's luster and downplay its fire—were all the rage during the Art Deco period, whereas the princess cut—which accentuates a diamond's fire rather than its luster—is currently gaining popularity. The princess cut is also popular amongst diamond cutters: of all the cuts, it wastes the least of the original crystal. The past decades have seen the development of new diamond cuts, often based on a modification of an existing cut. Some of these include extra facets. These newly developed cuts are viewed by many as more of an attempt at brand differentiation by diamond sellers, than actual improvements to the state of the art.

Quality

The quality of a diamond's cut is widely considered the most important of the four Cs in determining the beauty of a diamond; indeed, it is commonly acknowledged that a well-cut diamond can appear to be of greater carat weight, and have clarity and color appear to be of better grade than they actually are. The skill with which a diamond is cut determines its ability to reflect and refract light.

In addition to carrying the most importance to a diamond's quality as a gemstone, the cut is also the most difficult to quantitatively judge. A number of factors, including proportion, symmetry, and the relative angles of various facets, are determined by the quality of the cut and can affect the performance of a diamond. A poorly cut diamond with facets cut only a few degrees out of alignment can result in a poorly performing stone. For a round brilliant cut, there is a balance between "brilliance" and "fire". When a diamond is cut for too much "fire", it looks like a cubic zirconia which gives out much more "fire" than real diamond. A well executed round brilliant cut should reflect most light out from the tabletop and make the diamond appear white when viewed from the top. An inferior cut will produce a stone that appears dark at the center and in some extreme cases the ring settings may show through the top of the diamond as shadows.

Several different theories on the "ideal" proportions of a diamond have been and continue to be advocated by professional gemologists. Recently, there has been a shift away from grading cut by the use of various angles and proportions toward measuring the performance of a cut stone. A number of specially modified viewers have been developed toward this end. One result of this trend is the rise of the phrase "hearts and arrows", describing a characteristic pattern observable on stones exhibiting high symmetry. Hearts and arrows diamonds trade at a 10% to 20% premium to otherwise comparable diamonds.

The cutting process

Main article: Diamond cutting

The process of shaping a rough diamond into a polished gemstone is both an art and a science. The choice of cut is often decided by the original shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation of the weight, popularity of certain shapes amongst consumers and many other considerations. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.

Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. Since the per-carat price of diamond shifts around key milestones (such as 1.00 carat), many one-carat diamonds are the result of compromising "Cut" for "Carat". Some jewelry experts advise consumers to buy a 0.99 carat diamond for its better price or buy a 1.10 carat diamond for its better cut, avoiding a 1.00 carat diamond which is more likely to be a poorly cut stone.

Natural history

Formation

Diamond is formed by prolonged exposure of carbon deposits to high pressure and temperature. On Earth, the formation of diamonds is possible because there are regions deep within the earth that are at a high enough pressure and temperature that the formation of diamonds is thermodynamically favorable (see the diamond phase diagram and geotherms here). Under continental crust, diamonds form starting at depths of about 150 kilometers (90 miles), where pressure is roughly 5 gigapascals and the temperature is around 1200 degrees Celsius (2200 degrees Fahrenheit). Diamond formation under oceanic crust takes place at greater depths due to higher temperatures, which require higher pressure for diamond formation. Long periods of exposure to these high pressures and temperatures allow diamond crystals to grow larger.

Through studies of isotope ratios (similar to the methodology used in carbon dating), it has been shown that the carbon found in diamonds comes from both inorganic and organic sources. Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle. In contrast, eclogitic diamonds contain organic carbon from organic detritus that has been pushed down from the surface of the Earth's crust through subduction (see plate tectonics) before transforming into diamond. Diamonds that have come to the earth's surface are generally very old, ranging from under 1 billion to 3.3 billion years old.

Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles. Other forms include dodecahedra and cubes. Diamonds are commonly found coated in nyf, a gum-like skin.

Diamonds can also form in other natural high-pressure high-temperature events. Very small diamonds, known as microdiamonds or nanodiamonds, have been found in impact craters where meteors strike the Earth and create momentary zones of high pressure and temperature where diamond formation can occur. Microdiamonds are now used as one indicator of an ancient meteor strike. Especially ancient meteorites may contain "star dust", the remnants of dead stars, some of which is composed of extremely tiny diamond crystals.

Surfacing

Diamond-bearing rock is forced close to the surface through deep-origin volcanic eruptions. The magma for such a volcano must originate at a depth where diamonds can be formed, 150 kilometers (90 miles) deep or more (three times or more the depth of source magma for most volcanos); this is a relatively rare occurence. Below these typically small volcanos are formations known as volcanic pipes, which contain material that was pushed toward the surface of the earth by volcanic action, but did not erupt before the volcano became extinct. Diamond-bearing volcanic pipes are most commonly found in the oldest regions of continental crust, which relates to the fact that these areas are the coolest portions of the earth's crust, and therefore diamonds can form at the shallowest depths.

The magma in such volcanic pipes is usually one of two characteristic types, which cool into igneous rock known as either kimberlite or lamproite. The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks and material upward. These materials are characteristically rich in certain minerals (usually rich in magnesium), most notably serpentine. Kimberlite deposits are known as blue ground, or yellow ground at the surface where it has been weathered and oxidized, based on their appearance.

Once diamonds have been forced to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. A volcanic pipe containing diamonds is known as a primary source of diamonds. Secondary sources of diamonds include all areas where a significant number of diamonds, eroded out of their kimberlite or lamproite matrix, accumulate due to water or weather action. These include alluvial deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate due to their approximate size and density.

Diamonds can also be pushed to the surface through certain processes which may occur when two continental plates collide forcefully, although this phenomenon is less understood and currently assumed to be uncommon.

History

The history of diamond cutting can be traced to the late Middle Ages, before which time diamonds were enjoyed in their natural octahedral state. The first "improvements" on nature's design involved a polishing of the crystal faces—this was called the point cut. Later still, a little less than one half of the crystal would be sawn off, creating the table cut. Neither of these early cuts would reveal what diamond is prized for today; its strong dispersion or fire. At the time, diamond was valued chiefly for its brilliant lustre and superlative hardness; a table-cut diamond would appear black to the eye, as they do in paintings of the era.

In 1375, there was a guild of diamond polishers at Nürnberg.

In or around 1476 Lodewyk (Louis) van Berquem, a Flemish polisher of Bruges, introduced absolute symmetry in the disposition of facets. He cut stones in the shape known as pendeloque or briolette.

About the middle of the sixteenth century, the rose or rosette was introduced.

The brilliant cut was introduced in the middle of the seventeenth century. The first brilliants were known as Mazarins. They had 17 facets on the crown (upper half). They are called double-cut brilliants.

Vincent Peruzzi, a Venetian polisher, increased the number of crown facets from 17 to 33 (triple-cut brilliants), thereby increasing very much the fire and brilliancy of the cut gem, which were already in the double-cut brilliant incomparably better than in the rose. Yet diamonds of that cut, when seen nowadays, seem exceedingly dull compared to modern-cut ones.

Roughly 1900, the development of diamond saws and good jewellery lathes enabled the development of modern diamond cuts, chief among them the round brilliant cut. In 1919, Marcel Tolkowsky analyzed this cut. His calculations took both brilliance (the amount of white light reflected) and fire into consideration, creating a delicate balance between the two. His geometric calculations can be found in his book on Diamond Design.

See also: List of famous diamonds

The diamond industry

Main article: Diamond industry

The diamond industry can be broadly separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways.

Gem diamond industry

A large trade in gem-grade diamonds exists. Unlike precious metals such as gold or platinum, gem diamonds to not trade as a commodity: there is a substantial mark-up in the sale of diamonds, and there is not a very active market for resale of diamonds. One hallmark of the trade in gem-quality diamonds is its remarkable consolidation: wholesale trade and diamond cutting is limited to a few locations (most importantly Antwerp, London, Tel Aviv, and increasingly Gujarat), and a single company — De Beers — controls over half of all trade in diamonds.

The De Beers company holds a clearly dominant position in the industry, and has done so since its founding in 1888. De Beers owns or controls a significant portion of the world's production facilities (mines) and distribution channels for gem-quality diamonds. At one time it was thought over 80 percent of the world's rough diamonds passed through the Diamond Trading Company (DTC, a subsidiary of De Beers) in London, but presently the figure is estimated at around 60 percent. De Beers has used its monopoly position to establish strict price controls, and aggressively market diamonds directly to consumers in world markets.

In the late 1990s, Canadian prospectors discovered several rich sources of diamonds. For example, the Ekati Diamond Mine, which was opened in 1998, produces three million carats (600 kg) of rough diamond every year. The Diavik Diamond Mine was opened in 2004.

De Beers has actively promoted diamonds as being symbolic of eternity and love, and therefore the ideal jewel for an engagement or wedding ring. Their famously successful advertising campaigns have included measures such as:

• showing diamonds as wedding gifts in popular romantic movies
• publishing stories in magazines and newspapers which would emphasize the romantic value of diamonds and associate them with celebrities
• employing fashion designers and other trendsetters to promote the trend on radio and, later, television
• enlisting the Royal Family of the United Kingdom to directly promote diamonds.

This campaign was described by De Beers' PR agency N. W. Ayer as "a new form of advertising which has been widely imitated ever since" with "no brand name to be impressed on the public mind. There was simply an idea -- the eternal emotional value surrounding the diamond." Indeed, the campaign succeeded in reviving the American diamond market, which had been weakened by "competitive luxuries", and in opening new markets where none had existed before. In Japan, for example, diamonds were successfully promoted as a western symbol of status, which coincided with Japan's cultural opening after World War II. Japan, which had no diamond tradition before the De Beers campaign, is today the second largest market for retail diamonds.

The slogan "A Diamond is Forever", invented by N.W. Ayer, is one of the most successful slogans in marketing history. Its purpose is to prevent the creation of a secondary market by dissuading women from selling the diamonds they have received and by discouraging them from buying diamonds which other women have owned. The consequence of this is that retailers can sell diamonds at a high price without competition from a secondary market and to allow DeBeers to maintain control of the diamond trade at the wholesale level.

Sources

Historically diamonds were found in alluvial deposits in southern India which are now worked out. Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo and Sierra Leone. Revolutionary groups in some of those countries have taken control of diamond mines, using the conflict diamonds to finance their operations. In response to public concerns that their diamond purchases were contributing to war and human rights abuses in central Africa, the diamond industry and diamond-trading nations introduced the Kimberley Process aimed at ensuring that conflict diamonds do not becoming intermixed with the diamonds not controlled by such rebel groups.

There are also commercial deposits in the Northwest Territories of Canada, the Russian Arctic, Brazil and in Northern and Western Australia. Occasionally diamonds have been found in glacial deposits in Wisconsin and Indiana. The Wisconsin finds can be explained by recent Canadian discoveries, but the diamonds found in Indiana must have come from an as yet undiscovered source in Quebec as the movement of ice was from northeast to southwest. There is also a diamond mine at Crater of Diamonds State Park in Murfreesboro, Arkansas. Tiny nanometre-sized diamonds, often called nanodiamonds, are also found as presolar grains in primitive meteorites.

Diamonds have been manufactured synthetically for over fifty years, and very recently companies have begun marketing synthetic diamonds to the public as jewelry and in technology.

A city of major importance in diamond trade is Antwerp, Belgium. It is estimated that nearly 90 percent of the world's rough diamonds, 50 percent of cut diamonds, and 40 percent of industrial diamonds trade hands in Antwerp. The industry is represented by the Diamond High Council (HRD). Before Antwerp the port city of Bruges saw most diamond trade, holding its position since the 13th century. Toward the 15th century Bruges declined, its port choked with silt.

Antwerp had been the world centre of diamond trade since the 16th century, until the city's 1585 capture by the Spanish. Amsterdam then supplanted Antwerp as a trading centre, until the latter's resurgence beginning in the 19th century.

During the 1990s Israeli interests, centralized in Ramat Gan, acquired about 20% of the diamond trade, buying diamonds from Russia and from mines in Africa not controlled by De Beers. De Beers now deals only in diamonds from their own mines. A major diamond cutting industry has grown up in the state of Gujarat, India where 90% of the world's diamonds (as measured by number of diamonds) are cut by a workforce of 800,000. Small diamonds previously not worth cutting are cut in India, opening up a new market segment for small diamonds.

Symbolism

It is said the Greeks believed diamonds were tears of the gods; the Romans believed they were splinters of fallen stars. Many long dead cultures have sought the divine or the mystical in diamond, thereby explaining its specialities.

Perhaps the earliest symbolic use of diamonds was as the eyes of Hindu devotional statues. The diamonds themselves were thought to be endowments from the gods and were therefore cherished. The point at which diamonds assumed their divine status is not known, but early texts indicate they were recognized in India since at least 400 BC.

In western culture, diamonds are the traditional emblem of fearlessness and virtue. Although rarely seen in jewellery prior to the Baroque period, early examples of betrothal jewels incorporating diamonds include the Bridal Crown of Blanche (ca. 1370-1380) and the Heftlein brooch of Vienna (ca. 1430-1440), a pictorial piece depicting a wedding couple.

Today, diamonds are used to symbolize eternity and love, being often seen adorning engagement rings. This modern tradition can be directly traced to the marketing campaigns of De Beers, starting in 1938.

The diamond engagement ring is, however, not an original invention of De Beers. It can be traced to the marriage of Maximilian I (then Archduke of Austria) to Mary of Burgundy in 1477. While the act did much to advance the Habsburg empire, it did little to make the diamond ring a widely encountered expression of betrothal.

The inception of the engagement ring itself can be tied to the Fourth Lateran Council presided over by Pope Innocent III in 1215. Innocent declared a longer waiting period between betrothal and marriage; plain rings of gold, silver or iron were used earliest. Gems were more than baubles; they were important and reassuring status symbols to the aristocracy. Laws were passed to preserve a visible division of social rank, ensuring only the privileged wore florid jewels. As time passed and laws relaxed, diamonds and other gems became obtainable to the middle class.

The diamond is the birthstone for people born in the month of April.

The LifeGem company further taps modern symbolism by offering to synthetically convert the carbonized remains of people or pets into "memorial diamonds." However, many people still feel very uncomfortable at the thought of wearing the carbonized remains of people as jewelry.

See also

• Synthetic diamond
• Allotropes of carbon
• Conflict diamond
• List of minerals
• Material properties of diamond
• Diamond color
• Diamond clarity
• Diamond cut
• Diamond cutting
• List of famous diamonds

External links

Labs, cut, and general resources

• OctoNus Software has posted several diamond cut studies, by various authors. OctoNus, Moscow State University, Bruce Harding, and others have posted work there.
• Gemological Institute of America
• European Gemological Laboratory USA
• Smithsonian's exhibit of fancy color diamonds
• "The Nature of Diamonds" - American Museum of Natural History's online exhibition on diamonds. Detailed look at the history, art and science behind the stone.
• PBS Nature: Diamonds
• Adamas Gemological Laboratory makes spectrophotometer machines that measure the color of gems. The machines can be programmed to distinguish natural, artificial, and color-enhanced gems.

Chemistry and artificial diamonds

• Physical properties of diamond.
• "The New Diamond Age" Article about diamond manufacture from Sept. 2003 issue of Wired.
• NanoDiamond - nanotubes arranged in a diamond formation yielding a very high strength-to-weight ratio material.
• Diamond and Fullerenes models by Vincent Herr.
• Chemical & Engineering News article on man made diamonds.

Natural sources and marketing

• On conflict diamonds (UN)
• Diamonds from the Ekati mine
• Ekati diamond mine
• Diavik diamond mine
• Edward Jay Epstein: "Have You Ever Tried To Sell a Diamond? (subscription required)" The Atlantic Monthly, February 1982. About the history of the De Beers cartel, the modern marketing "invention" of diamonds, the market in diamonds and the problem of maintaining artificial scarcity; later collected in his book The Rise and Fall of Diamonds ISBN 0671412892
• The Straight Dope: Is a diamond's price a true measure of its value?
• An explanation of the distinction between a diamond and a carbonado.
• Events on the diamond market. From computer intelligent mining programs to new technologies in diamond grading.

References

• Tolkowsky, Marcel (1919). Diamond Design: A Study of the Reflection and Refraction of Light in a Diamond. London: E. & F.N. Spon, Ltd. (Web edition as edited by Jasper Paulsen, Seattle, 2001.)
• The Columbia Electronic Encyclopedia, Sixth Edition (2003). "Diamond". Retrieved March 9, 2005 at http://www.answers.com/topic/diamond.
• American Museum of Natural History. "The Nature of Diamonds". Retrieved March 9, 2005.

• Gemstones
• Minerals
• Native element minerals
• Superhard materials
• Materials