National Geographic : 1979 Jan
COURTESYSAMWAGSTAFF Greed spun a web that mantled the "Big Hole" of Kimberley in 1876 (above), ten years after the discovery of diamonds in South Africa. More than 1,600 claims, each 31 feet square in area and serviced by cables to the mine's rim, congested the site. Sides crumbled, causing cave-ins and deaths. Gradually claims were consolidat ed, until, in 1888, Cecil Rhodes bought out the other large claim holder, Barney Bar nato, and established the De Beers Con solidated Mines, Ltd. Today the firm controls 85 percent of the world market. The town of Kimberley (left) nudges up to the abandoned mine's sides. gem of choice for engagements and wed dings-the symbol of love's durability? The diamond has inspired courage, fear, and especially superstition. It is said that the 19th-century Afghan prince Shah Shuja en dured blinding and days of torture before surrendering the Koh-i -noor, often called the world's most famous diamond, now in the crown of the Queen Mother of England. He explained his adamant stand with some illogic: "It brings good luck." Even so desperate an optimist would not have been able to say the same about the Hope Diamond (page 112). Around it has been woven such a legend of intrigue, mur der, and disaster that all its owners from Louis XIV to American heiress Evalyn Walsh McLean were said to find tragedy accompanying the fabled blue stone. * And yet these mystic gems, like all dia monds, are simply carbon, one of the world's most plentiful elements. A colorless diamond is very pure carbon indeed, with exactly the same atoms as coal or graphite. (Impurities produce colored diamonds; nitrogen, for example, results in yellow stones.) What makes diamond a unique car bon is the way it was formed millions of years ago. Under intense heat and pressure of the earth's liquid magma, diamond atoms crystallized in a solid cubic pattern, giving the material its unsurpassed hardness. The Four C's Determine Worth Diamond values are determined by the four C's: carat weight, cut, clarity, and col or. Carat is an ancient term referring to the uniform weight of a carob seed. Now it has been set at 1/142 ounce, or 1/5 gram. Cut refers to the quality of polishing and shape of the finished diamond. The four most common shapes are pear, emerald, marquise, and-most popular-brilliant, a round cut with 58 mathematically deter mined facets precisely formed to enhance diamonds' high refraction, thereby produc ing gems filled with fire and sparkle. Clarity ranges from flawless (no visible imperfections under a ten-power loupe) to heavily flawed (defects visible to the unaid ed eye). The colorless diamond is generally the most valuable, except for the rare and *See "Questing for Gems," by George S. Switzer, in the December 1971 NATIONAL GEOGRAPHIC.