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THE BOOK OF DIAMONDS
at a glance. Generally artificial pearls are more brittle than the real gems.
Substances
used in jewelry not properly precious stones are: moonstones,
malachite, jet, jade, amber, coral, etc. Spinel is a mineral of
magnesia and alumina coming from impurities in the iron.
The
name corundum itself is of Indian origin and is applied only to the
opaque massive varieties of hard mineral next to those of diamonds,
generally of a dull color. Its composition is alumina, 98.5 per cent;
oxide of iron, 1 per cent; and lime, .05 per cent.
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116
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