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T
HE diamond
crystallizes in the isometric system, and is usually found as an
octahedron or as some modification of that form. It is 10 in the scale
of hardness and the hardest of all known substances. Its composition is
pure carbon. It has a greater refractive and dispersive power on light
than any other gem, and is the only one that is combustible. Its
specific gravity is about 3.525. In color its range is extensive, and
it is found in almost all the shades of the spectrum, more commonly,
however, white, yellow, brown ; rarely rose-red, red, blue, and green.
Ninety-five
per cent, of the diamonds at present obtained are from the Kimberley
Mines, Griqua Land West, South Africa. The remainder come from Brazil,
India, and Borneo. A few have been found recently in New South Wales,
and they are known to exist in the Ural Mountains. Since the discovery
of South African mines in 1867, and the opening a short time afterward
of 3,143 claims that are now consolidated into a small number of large
companies, all within a radius of a mile and a half, more diamonds have
been found than during the two preceding centuries throughout the whole
world. Over 9 tons (40,000,000 carats) of diamonds, valued in the rough
at $250,000,000, and after cutting at over $500,000,000, have been
taken from these mines. Diamonds are sold by the carat. The
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