With their clear brilliance, diamonds may have an icy appearance, but they are a hot-selling gemstone. Consumers in the United States alone purchased $9 billion worth of loose gem-quality diamonds in 2001. Although the U.S. accounts for less than one percent of total global gemstone production, America is the world’s largest diamond market.
Despite such strong demand, however, diamonds, like true friends, are not easy to come by. According to diamond experts at the Gemological Institute of America (GIA) in Carlsbad, Calif., 250 tons of earth must be mined to produce a single one-carat diamond, and fewer than 20 percent of the diamonds mined worldwide are gem-quality. In addition, only one polished diamond out of a thousand weighs more than one carat.
GIA, which created the International Diamond Grading System™, based on the Four Cs (color, clarity, cut, and carat weight) says diamonds were formed billions of years ago through a combination of tremendous pressure and temperatures of 2000º –3000º F at depths between 75 and 120 miles beneath the earth’s surface. But today’s diamond miners don’t have to dig that deep, because diamond crystals are found in volcanic kimberlitic pipes, which carried the crystals closer to the earth’s surface through volcanic activity. Diamonds can also be found in alluvial deposits where the crystals settle after being transported away from the kimberlite pipes by geologic activity, according to information from GIA’s Diamonds course.
Diamonds have been prized for thousands of years. The earliest written account of diamonds dates back to around 500 B.C., and, until the 18th century the only diamond mines were in India. As early as 1725, diamonds were discovered in South America. The discovery occurred in Minas Gerais, Brazil, just as the production in India was dwindling. In the 1840’s, diamonds were found in North America, although this was soon eclipsed by the discovery of diamonds in Africa and the ensuing Great Diamond Rush.
One of the most famous diamonds is the Great Star of Africa, which was cut from the world's largest rough diamond, the Cullinan I, weighing 530.2 carats. The historic Cullinan diamond, found in South Africa in 1905, weighed an astounding 3,106.75 carats. It was cut into the Great Star of Africa (Cullinan I), the Lesser Star of Africa (known as the Cullinan II, weighing 317.40 carats), and 103 other diamonds of nearly flawless clarity. The principal diamonds are mounted in the British crown jewels.
Australia produces the most diamonds by volume, and Botswana is first in value of diamonds produced, but North America is coming into its own with the opening of the Ekati Mine and others in Canada, which have the potential to produce at least 12 percent of the total world diamond production.
The U.S. has the world’s only diamond mine open to the public. The Crater of Diamonds State Park in Arkansas is a dig-for-fee operation for tourists and rock hounds. Since 1906, more than 70,000 diamonds have been discovered there, including the Uncle Sam diamond, weighing 40.23 carats. To date the Uncle Sam, discovered in 1924, is the largest diamond ever found in the U.S.
Sources: Gemological Institute of America