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CHAPTER IV
    KINDS AND OCCURRENCES OF GEM
                    MINERALS
         These gems have life in them: their colors speak,
         Say what words fail of.
                               -GEORGE ELIOT.
                    THE DIAMOND
THE diamond, generally conceded to take precedence over
all other gems, has long been the most coveted of gem
stones. In ancient times it was not common. Pliny says
it "was long known to none but kings, and to but very few
of them." At the present time, perhaps no other gem
stone is so greatly in demand notwithstanding the fact
that, with one or two exceptions, it commands the highest
price of any on the market.
  Knowledge of the diamond stretches far back into
antiquity, how far no one knows. Ptolemy mentions a
"diamond river" in India, and many ancient Sanscrit
manuscripts treat of the diamond in considerable detail.
It has also been asserted that the stone now known as the
Koh-i-noor belonged to Karna, King of Anga, 5,000 years
ago.
  The remarkable physical characteristics of the diamond
explain the esteem in which men hold it; no other mineral
equals it in hardness; in range of color it includes nearly
all the prismatic hues; its luster is peculiarly brilliant
and is superior to that of any other gem. To its refrac-
tive and dispersive powers is due the flash of colors char-
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