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THE DIAMOND
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of
the diamond and to favor the idea of the slow growth of large crystals
by accretion, instead of a sudden solidification in a fused mass. One
large diamond of 228 carats, found several years ago, was formed around
a small red diamond crystal. In another case the smaller enclosed
crystal was coated with apophylite.
White
specks and bubbles are common flaws. These vary in size and appearance,
some of them glistening in the interior with a vitreous luster, others
ranging from an icy to snowy whiteness. Some of these, apparently, are
hollow or gas-filled bubbles, while others are solid but imperfectly
crystallized sections. Glessen or glasses, are flat sectional streaks
of a similar nature, having an icy appearance. When large or abundant
in a crystal, they constitute a very bad imperfection, as they destroy
all but the surface brilliance of the stone. Diamonds of this character
are sometimes termed " shivery " and in this country are difficult to
sell at any price.
"
Clouds" are dark flat patches in the grain of the stone similar to the
glasses, but brownish or blackish. Unlike glasses they are seldom large
or numerous in a single stone, nor do they so completely destroy the
internal brilliancy. They consist apparently of inclusions of foreign
matter, or a fine dusting in the grain, of un-crystallized carbon. Some
scientists claim that all black and brown spots and clouds are
inclusions of foreign matter, probably titanic iron.
When
clouds or glasses reach the surface of a cut diamond they appear as
cracks, and if near the girdle are dangerous, the stone being liable to
split there under heat or a smart blow. Usually the break will not
extend
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