Cowboy

Much has been written about the racial mix of the cowboys in the West, but cowboys ranked low in the social structure of the period and there are no firm figures. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the now-familiar slogan "a diamond is forever". In pop culture, the cowboy and the gunslinger are often associated with one another. Ayer's multifaceted marketing campaign included product placement, advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. In the 1930s and 1940s, Western movies popularized the cowboy lifestyle but also formed persistent stereotypes. N.W. Meanwhile, ranches multiplied all over the developing West, keeping cowboy employment high, if somewhat more settled. Ayer & Son, the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before.

Smaller cattle drives continued at least into the 1940s, with Arizona cattle driven to the railhead at Magdalena, New Mexico. N.W. By the 1890s, the open ranges of the Indian Territory were gone and the large cattle drives from Texas to the railheads in Kansas were over. The De Beers diamond advertising campaign is acknowledged as one of the most successful and innovative ones in history. Such hazardous work in isolated conditions bred a tradition of self-dependence and individualism, exemplified in their songs and poetry. De Beers has used its monopoly position to establish strict price controls, and aggressively market diamonds directly to consumers in world markets. Over time, the cowboys of the American West developed a culture of their own, a blend of frontier and Victorian values. 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.

Sharing the same base, their traditions became indistinguishable with a few regional differences still remaining. The company and its subsidiaries own mines that produce some 40 percent of annual world diamond production, and control distribution channels handling nearly two thirds of all gem diamonds. Following the Civil War, their culture diffused eastward and northward combining with the earlier cowboy tradition that was following the cattle trails out of Texas northward and westward. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and distribution channels for gem-quality diamonds. Buckaroo is the anglicized pronunciation of vaquero and is still a common term in the Great Basin and many areas of California and the Pacific Northwest. The De Beers company holds a clearly dominant position in the industry, and has done so since soon after its founding in 1888. The buckaroo, also a cowboy of the vaquero tradition, developed in California and bordering territories during the Spanish Colonial period. The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers (the most important being Antwerp).

Here they were absorbed by the Mexican vaquero culture, borrowing vocabulary and attire from their counterparts. They are based in Johannesburg, South Africa and London, England. Following Texas independence in 1836 even more Americans immigrated into Texas and to the empresario ranching areas. One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to a few locations (most importantly New York, Antwerp, London, Tel Aviv, Amsterdam and Surat), and a single company—De Beers—controls over half of all trade in diamonds. Austin and his East Coast comrades became the first English speaking Mexicans. Unlike precious metals such as gold or platinum, gem diamonds do 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. In 1821 Stephen F. A large trade in gem-grade diamonds exists.

In the early 1600s, Spain, and later Mexico, began offering empresario grants in what would later be Texas to Americans who agreed to become citizens and convert to Catholicism. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways. In the northern parts of Mexico (New Mexico) in its original configuration included most of the territory of the American southwest including Texas. The diamond industry can be broadly separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. Actually, what is usually believed to be an American icon, is in reality a New Hispanic tradition originated in the Central States of Mexico, Jalisco and Michoacan, where the Mexican cowboy would eventually be known as "charro". The largest flawless and colorless (grade D) diamond is the Millennium Star (1990) at 203.04 carats. During the 16th century, they brought the tradition with them to the New World through New Spain (later Mexico). One of the diamonds cut from it, Cullinan I or the Great Star of Africa, was formerly the largest cut diamond at 530.2 carats, but now that title has been taken by the Golden Jubilee (1985), a 545.67 carat yellow-brown diamond.

In fact the Spanish invented what we now know as the cowboy tradition beginning in the Middle Ages in Spain. The Cullinan Diamond, owned by Queen Elizabeth II was the largest gem-quality rough diamond ever found (1905), at 3,106.75 carats. The Spanish were adept at herding livestock. A number of large diamonds have become historically significant objects, as their inclusion in various sets of crown jewels and the purchase, sale, and sometimes theft of notable diamonds, have sometimes become politicized. . Popularity continued to rise as new cuts were developed that enhanced the diamond's aesthetic appeal, and has largely continued unabated to this day; diamonds have proven popular with all classes in society as their cost has become within reach. In addition to ranch work, some cowboys work in and participate in rodeos, and many cowboys work only in the rodeo. However, within a century diamonds were popular gems among the moneyed aristocratic and merchant classes, and by at latest 1477 had begun to be used in wedding rings.

The cowboy is in charge of the horses, as is the wrangler. In the 13th century, King Louis IX of France established a law that only the king could own diamonds. A cowboy (Spanish vaquero) tends cattle and horses on cattle ranches in North and South America. The rise in popularity of diamonds as gems seems to have paralleled increasing availability through European history. Computer science: Cowboy/cowgirl, as in a really skillful computer hacker or computer programmeror video games. In 1919, Marcel Tolkowsky developed an ideal round brilliant cut design that has set the standard for comparison of modern gems; however, diamond cuts have continued to be refined. Sports: Cowboy action shooting, Rodeo, Indian rodeo, Charreada. Over the following centuries, various diamond cuts were introduced which increasingly demonstrated the fire and brilliance that makes diamonds treasured today: the table cut, the briolette (around 1476), the rose cut (mid-16th century), and by the mid-17th century, the Mazarin, the first brilliant cut diamond design.

Music: Western Music, Western swing, List of famous Cowboy songs. By 1375, a guild of diamond polishers had been established at Nuremberg. Television: TV Western. During this time, the taboo against cutting diamonds into gem shapes, which was established over 1,000 years earlier in the traditions of India, ended allowing the development of diamond cutting technology to begin in earnest. Film: Western movie, List of Western movies. Around 1300, the flow of diamonds into Europe increased via Venice's trade network, with most flowing through the low country ports of Bruges, Antwerp, and Amsterdam. Literature: Western fiction, List of Western fiction authors, Cowboy poetry. Until the late Middle Ages, diamonds were most prized in their natural octahedral state, perhaps with the crystal surfaces polished to increase luster and remove foreign material.

Fine art: Cowboy Artists of America. In Europe, however, diamonds disappeared for almost 1,000 years following the rise of Christianity because of two effects: early Christians rejected diamonds because of their earlier use in amulets, and Arabic traders restricted the flow of trade between Europe and India. Saddle bags; a bag which can be mounted to the saddle for carrying various sundry items and extra supplies. Archeological evidence from Yemen suggests that diamonds were used as drill tips as early as the 4th century BCE. Bridle; a Westen bridle usually has a curb bit and long split reins to control the horse in many different situations. In China, diamonds seem to have been used primarily for engraving jade and drilling holes in beads. Saddle blanket; a blanket or pad is required under the Western saddle to provide comfort and protection for the horse. The Roman writer Pliny the Elder noted diamond's ornamental uses, as well as its usefulness to engravers because of its hardness, in his work Naturalis Historia.

Western Saddle; a saddle with specially designed for working with cattle; it has stirrups to allow the rider to stand or resist the pull of livestock while working, a horn so the lariat can be snubbed, tiedowns to provide secure mountings for any additional equipment needed for work on the ranch, and various other modifications. Diamonds were traded to both the east and west of India and were recognized by various cultures for their gemological or industrial uses. Cow dog; many people, including cowboys, find a herding dog invaluable in locating and controlling livestock. At that scale, the surface of the modern diamond-polished corundum closely resembled that of the axes; however, the polishes of the latter were superior. Occasionally cowboys will carry a pistol when not physically working cattle, especially in brushy areas. Although there are diamond deposits now known to exist close to the burial sites, no direct evidence of coeval diamond mining has been found: the researchers came to this conclusion by polishing corundum using various lapidary abrasives and modern techniques then comparing the results using an atomic force microscope. Rifle; a weapon needed to protect the livestock from predation by wild animals. team of archaeologists reported the discovery of four corundum-rich stone ceremonial burial axes originating from China's Liangzhu and Sanxingcun cultures (4000 BCE–2500 BCE) which, because of the axes' specular surfaces, the scientists believe were polished using diamond powder [2] [3].

Spurs; a tool, attached to the rider's heel, designed to help a rider communicate with the horse when the hands are busy or when it is too noisy for oral commands. In February 2005, a joint Chinese-U.S. Lariat; from the spanish "la riata," meaning "the rope," a tightly twisted stiff rope with a loop at one end enabling it to be thrown to catch animals (sometimes called a lasso, especially in the East). Ownership was restricted among various castes by color, with only kings being allowed to own all colors of diamond. Chaps; guards worn to protect the legs when riding through heavy brush or during rough work with the livestock. Diamonds quickly became associated with divinity, being used to decorate religious icons, and were believed to bring good fortune to those who carried them. Jeans, or other sturdy tight-fitting pants; heavy pants designed to protect the legs and snug fitting to prevent the pants legs from snagging on brush, corral equipment, and other hazards. The earliest written reference can be found in the Sanskrit text Arthasastra, which was completed around 296 BCE, describes diamond's hardness, luster, and dispersion.

Cowboy boot; a boot with a high top to protect the lower legs, pointed toes to help guide the foot into the stirrup, and high heels to keep the foot from slipping through the stirrup while working in the saddle. Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could then be found. Cowboy hat; a hat with a wide brim to protect from the sun and the elements; there are many styles, probably influenced by both the Mexican sombrero and US (and Confederate) Cavalry hats. However, cleanliness might reflect a diamond's sentimental value: some jewelers have noted a correlation between ring cleanliness and marriage quality [1]. Cleanliness does not affect the diamond's market value, as any competent jeweler will clean the diamond before offering it for sale. Some jewelers provide their customers with ammonia-based cleaning kits; ultrasonic cleaners are also popular.

Maintaining a clean diamond can sometimes be difficult, as jewelry settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Current practice is to thoroughly clean a diamond before grading its color. Historically, some jewelers' stones were misgraded because of smudges on the girdle, or dye on the culet. Colored dye or smudges can affect the perceived color of a diamond.

Even a thin film absorbs some light that could have been reflected to the person looking at the diamond. Water, dirt, or grease on the bottom of a diamond interferes with the diamond's brilliance and fire. Dirt or grease on the top of a diamond reduces its luster. A clean diamond is more brilliant and fiery than the same diamond when it is "dirty".

Although it is not one of the four Cs, cleanliness affects a diamond's beauty as much as any of the four Cs. 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. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. 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%.

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. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. 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 process of shaping a rough diamond into a polished gemstone is both an art and a science.

EightStar Diamond has results of the FireScope. Hearts on Fire Diamond has results of the Hearts and Arrows viewer. Solasfera Diamond has results of Hearts and Arrows viewer, GemEx BrillianceScope, and FireScope. Along with this shift there are a few companies that provide results on these viewers and machines in addition to the original 4c's.

These viewers and machines often help consumers determine the light preformance results of the diamond in addition the the traditional 4 C's. SymmetriScope or IdealScope (tests for light leakage, light return and proportions), Hearts and Arrows Viewer (test for "hearts and arrows" characteristic pattern observable on stones exhibiting high symmetry), GemEx BrillianceScope (tests for direct light performance results of a diamond), Isee2 Machine (tests for diffused light performance results of a diamond), and ASET (test for AGS cut grade). They included the FireScope, a.k.a. A number of specially modified viewers and machines have been developed toward this end.

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. Several different theories on the "ideal" proportions of a diamond have been and continue to be advocated by professional gemologists. 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. 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.

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 off much more "fire" than real diamond. A poorly cut diamond with facets cut only a few degrees out of alignment can result in a poorly performing stone. 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. 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.

The skill with which a diamond is cut determines its ability to reflect and refract light. 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. 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. Some of these include extra facets.

The past decades have seen the development of new diamond cuts, often based on a modification of an existing cut. The princess cut is also popular amongst diamond cutters: of all the cuts, it wastes the least of the original crystal. Cuts are influenced heavily by fashion: the baguette cut—which accentuates a diamond's luster and downplays its fire—was 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. Generally speaking, these "fancy cuts" are not held to the same strict standards as Tolkowsky-derived round brilliants and there are less specific mathematical guidelines of angles which determine a well-cut stone.

Diamonds which are not cut to the specifications of Tolkowsky's round brilliant shape (or subsequent variations) are known as "fancy cuts." Popular fancy cuts include the baguette (from the French, resembling a loaf of bread), marquise, princess (square outline), heart, briolette (a form of the rose cut), and pear cuts. Diamonds are cut into a variety of shapes that are generally designed to accentuate these features. Diamonds do not show all of their beauty as rough stones; instead, they must be cut and polished to exhibit the characteristic fire and brilliance that diamond gemstones are known for. Mathematically, the diameter in millimeters of a round brilliant should approximately equal 6.5 times the cube root of carat weight, or 11.1 times the cube root of gram weight.

Typically a round brilliant 1.0 carat diamond should have a diameter of about 6.5 mm. Another quick indication is the overall diameter. "Ideal" round brilliant diamonds should not have a depth percentage greater than 62.5%. The depth percentage is the overall quickest indication of the quality of the cut of a round brilliant.

So a poorly cut 1.0 carat diamond may have the same diameter and appear as large as a 0.85 carat diamond. Neither of the these tactics make the diamond appear any bigger, but it also greatly reduces the sparkle of the diamond. There is a financial premium for a diamond that weighs the magical 1.0 carat, so often the girdle is made thicker or the depth is increased. However, there is a small range in which the diamond can be considered "ideal." Today, because of the relative importance of carat weight in society, many diamonds are often intentionally cut poorly to increase carat weight.

The further the diamond's characteristics are from Tolkowsky's ideal, the less light will be reflected. A normal girdle should be about 1%–2% of the overall diameter. However, a thin girdle is required in reality in order to prevent the diamond from easily chipping in the setting. Tolkowsky's ideal dimensions did not include a girdle.

This should be a negligible diameter, otherwise light leaks out of the bottom. The culet is the tiny point at the bottom of the diamond. Tolkowsky defines the ideal dimensions to have:. The function of the crown is to diffuse light into various colors and the pavilion's function to reflect light back through the top of the diamond.

The girdle is the thin unpolished middle. The modern round brilliant has 57 facets (polished faces), counting 33 on the crown (the top half), and 24 on the pavilion (the lower half). He developed the round brilliant cut by calculating the ideal shape to return and scatter light when a diamond is viewed from above. The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky.

Round brilliant diamonds, the most common, are guided by these specific guidelines, though fancy cut stones are not able to be as accurately guided by mathematical specifics. There are mathematical guidelines for the angles and length ratios at which the diamond is supposed to cut at in order to reflect the maximum amount of light. Often diamond cut is confused with "shape.". The cut of a diamond describes the quality of workmanship and the angles to which a diamond is 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. Diamond cutting is the art and science of creating a gem-quality diamond out of mined rough. Gemologists have developed rating systems for fancy colored diamonds, but they are not in common use because of the relative rarity of colored diamonds. Intense yellow coloration is considered one of the fancy colors, and is separate from the color grades of white diamonds.

Diamonds with unusual or intense coloration are sometimes labeled "fancy" by the diamond industry. A variety of impurities and structural imperfections cause different colors in diamonds, including yellow, pink, blue, red, green, brown, and other hues. 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. In contrast to yellow or brown hues, diamonds of other colors are much rarer and more valuable.

N-Y are usually appear light yellow or brown. Diamonds graded D-F are considered "colorless", G-J are considered "near-colorless", K-M are "slightly colored". Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades.

The system uses a benchmark set of either natural diamonds of known color grade, or precision-crafted cubic zirconia; test lighting conditions are also standardized and carefully controlled. The GIA has developed a rating system for color in white diamonds, from "D" to "Z" (with D being "colorless" and Z having a bright yellow coloration), which has been widely adopted in the industry and is universally recognized, superseding several older systems once used in different countries. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration due to this effect undetectable. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint.

Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. 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. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice.

However, in reality almost no gem-sized natural diamonds are absolutely perfect. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. (see the main article for more detail). Diamonds are graded by the major societies on a scale ranging from Flawless to Imperfect.

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

Of that top 20 percent, a significant portion contains an inclusion or inclusions that are visible to the naked eye upon close inspection. 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. Diamonds become increasingly rare when considering higher clarity gradings. The Gemological Institute of America (GIA) and others have developed systems to grade clarity, which are generally based on those inclusions which are visible to a trained professional when a diamond is viewed from above, under 10x magnification.

The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. 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. Clarity is a measure of internal defects of a diamond called inclusions. is also widely used for diamond necklaces, bracelets and other similar jewelry pieces.

T.c.w. when placed for sale, indicating the mass of the diamonds in both earrings and not each individual diamond. Diamond solitaire earrings, for example, are usually quoted in t.c.w. 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.

Because of this, diamond prices (particularly among wholesalers and other industry professionals) are often quoted per carat, rather than per stone. 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. In the wholesale trade of gem diamonds, carat is often used in denominating lots of diamonds for sale. Jewelers often trade diamonds at negotiated discounts off the Rapaport price (e.g., "R -3%").

A weekly price list published by Rapaport of New York, of diamond prices per carat, for different diamond cuts, clarity and weights, is currently considered the de-facto retail price baseline. As an example, a 0.95 carat diamond may have a significantly lower price per carat than a comparable 1.05 carat diamond, because of differences in demand. 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. The price per carat does not increase smoothly with increasing size.

A review of comparable diamonds available for purchase in September 2005 demonstrates this effect (approximate prices for round cut, G color, VS2 diamonds with "1A" cut grade, as listed on http://www.pricescope.com):. All else being equal, the value of a diamond increases exponentially in relation to carat weight, since larger diamonds are both rarer and more desirable for use as gemstones. The point unit—equal to one one-hundredth of a carat (0.01 carat, or 2 mg)—is commonly used for diamonds of less than one carat. One carat is defined as exactly 200 milligrams (about 0.007 ounce).

The carat weight measures the mass of a diamond. While carat weight and cut angles are mathematically defined, the clarity and color are judged by the trained human eye and are therefore open to slight variance in interpretation. There are four major gemological associations which "certify" diamonds: that is, define the four Cs of a diamond. Cleanliness also dramatically affects a diamond's beauty.

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. Other characteristics not described by the four Cs can and do influence the value or appearance of a gem diamond. 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. More detailed information from within each characteristic can then be used to determine actual market value for individual stones.

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. 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. 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. The dispersion of white light into a rainbow of colors, known in the trade as fire, is the other primary characteristic of gem diamonds, and has been highly prized throughout history.

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. Diamonds can also be brought 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. Diamonds have also rarely been found in deposits left behind by glaciers (notably in Wisconsin and Indiana); however, in contrast to alluvial deposits, glacial deposits are not known to be of significant concentration and are therefore not viable commercial sources of diamond. These include alluvial deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their approximate size and density.

Secondary sources of diamonds include all areas where a significant number of diamonds, eroded out of their kimberlite or lamproite matrix, accumulate because of water or weather action. A volcanic pipe containing diamonds is known as a primary source of diamonds. 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. Kimberlite deposits are known as blue ground for the deeper serpentinized part of the deposits, or as yellow ground for the near surface smectite clay and carbonate weathered and oxidized portion.

The most common indicator minerals are chromian garnets (usually bright red Cr-pyrope, and occasionally green ugrandite-series garnets), eclogitic garnets, orange Ti-pyrope, red high chromian spinels, dark chromite, bright green Cr-diopside, glassy green olivine, black picroilmenite, and magnetite. These minerals are rich in chromium (Cr) or titanium (Ti), elements which impart bright colors to the minerals. Certain indicator minerals typically occur within diamondiferous kimberlites and are used as mineralogic tracers in the search for diamond deposits by prospectors. These rocks are characteristically rich in magnesium bearing olivine, pyroxene, and amphibole minerals which are usually altered to serpentine under near surface conditions.

The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks and material upward. The magma in such volcanic pipes is usually one of two characteristic types, which cool into igneous rock known as either kimberlite or lamproite. 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. Below these typically small surface volcanic craters 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 volcanic activity ceased.

The magma for such a volcano must originate at a depth where diamonds can be formed, 90 miles (150 km) deep or more (three times or more the depth of source magma for most volcanoes); this is a relatively rare occurrence. Diamond-bearing rock is forced close to the surface through deep-origin volcanic eruptions. Microdiamonds are now used as one indicator of ancient meteorite impact sites. Very small diamonds, known as microdiamonds or nanodiamonds, have been found in impact craters where meteors strike the Earth and create shock zones of high pressure and temperature where diamond formation can occur.

Diamonds can also form in other natural high-pressure, high-temperature events. Diamonds (especially those from secondary deposits) are commonly found coated in nyf, an opaque gum-like skin. This is all due to the conditions in which they form. Sometimes they are found grown together or form double "twinned" crystals grown together at the surfaces of the octahedron.

The crystals can have rounded off and unexpressive edges and can be elongated. As diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, octahedron, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles. Diamonds that have come to the Earth's surface are generally very old, ranging from under 1 billion to 3.3 billion years old.

These two different source carbons have measurably different ¹³C:¹²C ratios. 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. Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle. Through studies of carbon isotope ratios (similar to the methodology used in carbon dating) except using the stable isotopes C-12 and C-13, it has been shown that the carbon found in diamonds comes from both inorganic and organic sources.

Long periods of exposure to these high pressures and temperatures allow diamond crystals to grow larger. Diamond formation under oceanic crust takes place at greater depths because of higher temperatures, which require higher pressure for diamond formation. 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). 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).

Diamond is formed by prolonged exposure of carbon bearing materials to high pressure and temperature.
. Because diamond has such high thermal conductance it is already used in semiconductor manufacture to prevent silicon and other semiconducting materials from overheating. 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.

Most natural blue diamonds contain boron atoms which replace carbon atoms in the crystal matrix, and also have high thermal conductivity. Unlike most electrical insulators, diamond is a good conductor of heat because of the strong covalent bonding within the crystal. Blue diamonds which are not boron-doped, such as those recently recovered from the Argyle diamond mine in Australia that owe their color to an overabundance of hydrogen atoms, are not semiconductors. Blue diamonds owe their semiconductive property to boron impurities, which act as a doping agent and cause p-type semiconductor behavior.

Except for most blue diamonds, which are semiconductors, diamonds are good electrical insulators. Most diamonds show no fluorescence although colored diamonds show a wider range of fluorescence than the blue fluorescence normally observed in clear diamonds. Nearly all diamonds fluoresce bluish-white, yellow or green under X-rays and this property is used extensively in mining to separate the fluorescing diamond from the non-fluorescing rock. Some diamonds exhibit fluorescence of various colors (predominately blue) under long wave ultraviolet light.

This is owed to their high refractive index of 2.417 (at 589.3 nm), which causes total internal reflection to occur. 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. 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. Diamonds exhibit a high dispersion of visible light.

However, owing to a very large kinetic energy barrier, diamonds are metastable; under normal conditions, it would take an extremely long time (possibly more than the age of the Universe) for diamond to decay into graphite. This was shown in the late 18th century, and previously described during Roman times. Diamonds will burn at approximately 800 degrees Celsius, providing that enough oxygen is available. At surface air pressure (one atmosphere), diamonds are not as stable as graphite, and so the decay of diamond is thermodynamically favorable (ΔG = −2.99 kJ / mol).

The most common impurity, nitrogen, causes a yellowish or brownish tinge. Most diamond impurities replace a carbon atom in the crystal lattice. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Diamonds with a detectable hue to them are known as colored diamonds.

Diamonds occur in a variety of transparent hues — colorless, white, steel, blue, yellow, orange, red, green, pink, brown—or colored black. Diamonds cut into certain particular shapes are therefore more prone to breakage than others. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Toughness relates to a material's ability to resist breakage from forceful impact.

Unlike hardness, which only denotes resistance to scratching, diamond's toughness is only fair to good. Unlike many other gems, it is well-suited to daily wear because of 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. Because it can only be scratched by other diamonds, it maintains its polish extremely well, keeping its luster over long periods of time. The hardness of diamonds also contributes to its suitability as a gemstone.

Industrial applications, especially as drill bits and engraving tools, also date to ancient times. Industrial-grade diamonds are either unsuitable for use as gems or synthetically produced, which lowers their price and makes their use economically feasible. Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most other diamonds, which are excellent electrical insulators. Common industrial adaptations of this ability include diamond-tipped drill bits and saws, or use of diamond powder as an abrasive.

As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. It is one of the most known and most useful of more than 3,000 known minerals. Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the ideal material for cutting and grinding tools. 1990).

Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws and defect planes in the crystal lattice all of which affect their hardness (Taylor et al. Their hardness is considered to be a product of the crystal growth form, which is single stage growth crystal. These diamonds are generally small, perfect to semiperfect octahedra and are used to polish other diamonds. The hardest diamonds in the world are diamonds from the New England area in New South Wales, Australia.

However, aggregated diamond nanorods, an allotrope of carbon first synthesized in 2005, are now believed to be even harder than diamond. Diamond's hardness has been known since antiquity, and is the source of its name. 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. A colorless, grey or black diamond with a tiny radial structure is a spherulite.

A cryptocrystalline variety of diamond is called carbonado. Lonsdaleite is a polymorph of diamond (and a distinct mineral species) that crystallizes with hexagonal symmetry; it is rarely found in nature, but is characteristic of synthetic diamonds. Other elements of the carbon group such as silicon have forms analogous to diamond. Graphite, another allotrope of carbon, has a rhombohedral crystal structure and as a result shows dramatically different physical characteristics — contrary to diamond, graphite is a very soft, dark grey, opaque mineral.

The tetrahedral arrangement of atoms in a diamond crystal is the source of many of diamond's properties. The unit cell of diamond has a two atom basis at (0,0,0) and (1/4,1/4,1/4), which means half of the atoms are at lattice points and the other half are offset by (1/4,1/4,1/4), where 1 is the length of a side of the unit cell. Diamonds typically crystallize in the face-centered cubic crystal system and consist of tetrahedrally bonded carbon atoms. These properties form the basis for most modern applications of diamond.

Most notable among these properties are the extreme hardness of diamond, its high dispersion index, and high thermal conductivity. Humans have been able to adapt diamonds for many uses because of the material's exceptional physical characteristics. Diamond is a transparent crystal of pure carbon consisting of tetrahedrally bonded carbon atoms. See also: Crystallographic defects in diamond.

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. There are also allegations that the De Beers Group misuses its dominance in the industry to control supply and manipulate price via monopolistic practices. The mining and distribution of natural diamonds are subjects of frequent controversy—such as with concerns over the sale of conflict diamonds by African paramilitary groups.

They are generally mined from volcanic pipes, which are deep in the Earth where the high pressure and temperature enables the formation of the crystals. Most natural diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, Russia, Brazil, and Australia. Although nearly four times the mass of natural diamonds are produced as synthetic diamond each year, the vast majority of synthetic diamond production remains small, imperfect diamonds suitable only for industrial-grade use, with gem-quality synthetic diamonds only recently becoming available. Popularity of diamonds has risen since the 19th century because of improved cutting and polishing techniques, and they are commonly judged by the "four Cs": carat, clarity, color, and cut.

They have been treasured as gems since their use as religious icons in India at least 2,500 years ago—and usage in drill bits and engraving tools also dates to early human history. The name "diamond" derives from the ancient Greek adamas (αδάμας; "impossible to tame"). About 130 million carats (26,000 kg) are mined annually, with a total value of nearly USD $9 billion. Diamonds are specifically renowned as a mineral with superlative physical qualities - they make excellent abrasives because they can only be scratched by other diamonds, which also means they hold a polish extremely well and retain luster.

Diamond is one of the two best known forms (or allotropes) of carbon, whose hardness and high dispersion of light make it useful for industrial applications and jewelry (the other equally well known allotrope is graphite). Crown Depth (Depth of crown divided by crown diameter) = 16.2%. Pavilion Depth (Depth of pavilion divided by overall diameter) = 43.1%. Crown Angle (Angle between the girdle and the crown) = 34.5°.

Pavilion Angle (Angle between the girdle and the pavilion) = 40.75°. Depth percentage (Overall depth divided by the overall diameter) = 59.3%. Table percentage (table diameter divided by overall diameter) = 53%. European Gemological Laboratory (EGI) has a similar reputation to the IGL.

International Gemological Laboratory (IGL) is a generally respected laboratory but suffers from a negative industry reputation for its grading practices, which are perceived by critics as being either less conservative or less consistent than the GIA and AGS. American Gemological Society (AGS) is not as widely recognized nor as old as the GIA, but garners an equally high reputation. Gemological Institute of America (GIA) was the first laboratory to issue modern diamond reports, and holds the highest reputation amongst gemologists for its consistent, conservative grading.