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Diamonds Are A Girls Best Friend
The great beauty and scarcity of transparent diamonds make them highly valued as gems. The diamond is the birthstone for the month of April, and it is by far the most popular gem for engagement and wedding rings. The diamond is also an ideal industrial tool because it is the hardest natural substance known.
The unit of weight for gems and industrial diamonds is the metric carat. One metric carat is equal to 0.2 grams or to 0.007 ounces.
Men have long been fascinated by unusually large and beautiful diamonds. Women even moreso.
One of the earliest known large stones was the Great Mogul, a famous Indian diamond of about 280 carats. It has been lost since 1665 and may have been cut into smaller diamonds.
The Hope diamond, which is now in the Smithsonian Institution in Washington, B.C., is a 44V2-carat blue stone. It first appeared in 1830 and is believed to have been cut from a 68-carat diamond stolen from the French government in 1792. The 140.5-carat Regent diamond was stolen at the same time as the Hope diamond. The Regent diamond was recovered and later embellished the hilt of Napoleon's sword.
The Cullinan was the world's largest diamond. It was found in South Africa in 1905 and weighed 3,106 carats, which is a little more than IVs pounds. The Cullinan was cut into 9 large gems and also 96 smaller gems. The two largest gems are now part of the British Crown jewels and the other large gems are the personal property of the British royal family.
The second largest diamond yet discovered, the Excelsior, was found in South Africa in 1893. It weighed 995 carats and was cut into a number of gems. In 1972, the third largest diamond, the Star of Sierra Leone, was discovered there. Since it is at present intact, it is the largest existing diamond.
Diamonds are best known as precious stones, but the inferior varieties called bort and carbonado are very important to industry. Most industrial diamonds are crushed into either powder or grit and used to make grinding wheels and disks for sharpening tungsten carbide tools and for shaping quartz, ceramic, and glass articles. Others are used to make wire-drawing dies. These dies are diamonds in which small holes are drilled. When a wire is drawn through the hole, it is reduced to the diameter of the hole.
Many diamonds are used in diamond drills. Diamond drills are hollow cylinders with diamonds mounted in their rims. When the cylinder is rotated, the drill advances, leaving a central core of the materials being drilled. The diamond drill is used to explore for mineral deposits; to test concrete dam, bridge, and building foundations; and to drill oil wells.
Color. The most valuable gem diamonds are either transparent and colorless or a very faint blue, However, such diamonds are rare, and most gem diamonds have tinges of yellow or brown, although some have very delicate green, pink, or orange tints. Red diamonds are extremely rare. The industrial diamonds, bort and carbonado, are generally brown, black, or grayish black.
Fire. The property of diamonds that is popularly called fire comes from their great ability to disperse white light into its component colors. When white light enters a diamond, the different colors are separated and emerge as red, orange, yellow, green, blue, and violet light. In this way, the diamond is given its fiery appearance.
Brilliance. A diamond's brilliance comes from its ability to collect light entering its side and top facets. Most of this light, after being reflected within the diamond, then emerges from the top facets, giving diamond its brilliant appearance. Other gems and cut glass are not as brilliant as diamond because a significant part of their light emerges from side and bottom facets, where it does not add to the stone's brilliance.
Hardness. Diamonds attain their extreme hardness because of the strong bonds of attraction between their carbon atoms and the high number of bonds per atom. These factors, together with the fairly close packing of carbon atoms, make diamond the hardest natural substance known. Diamonds, although hard, are also brittle, and care must be taken not to shatter them while they are being cut.
Structure. Diamonds found in nature may be rough and pebble-like as a result of irregularities of crystal growth. When a rough diamond is properly cleaved, however, it takes on a characteristic crystal shape. This shape results from the crystalline arrangement of the diamond's carbon atoms.
Diamonds usually have an 8-sided, or octahedral, crystal form. An octahedral crystal is shaped like two square-based pyramids placed base to base. The cleavage of a diamond takes place parallel to the octahedral faces. Other crystalline forms that diamond takes are cubes (6-sided crystals), dodecahedrons (12-sided crystals), trisoctahedrons (24-sided crystals), and combinations of these forms.
History of Diamonds
India was the world's first and only source of diamonds until the 1720's, when diamonds were discovered in Brazil. By 1740, Brazil was the world's largest diamond producer. Brazilian diamond supremacy lasted
until 1867, when diamonds were found on the bank of the Vaal River in South Africa. Within three years about 10,000 prospectors were sifting river gravel in search of diamonds. The search spread to higher ground late in 1870, when diamond pipes were found at Bultfontein, where the first mine in the Kimberley district was established. Diamond pipes were found at Jagersfontein in 1871.
At first African pipes were mined by individual prospectors working 31-foot-square claims. These small claims were combined by the Englishmen Cecil Rhodes and Barnett Barnato. Rhodes set up the De Beers Mining Company. When he bought Barnato's Kimberley mine, the name of the company was changed to De Beers Consolidated Mines, Ltd. By 1889, Rhodes had established a South African diamond monopoly. The De Beers Company still markets most of the world's diamonds.