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OTHER PRECIOUS STONES
Several weighing over 100 carats, are exhibited from time to time at the courts of Europe.
Topaz,
zircon, emerald, garnet, quartz, amethyst, onyx, agate, opal, and
pearls found in the shells of oysters are made up of the composition of
silica, carbonates and organic matter.
The
topaz affords a striking illustration of the vicissitudes of fashion.
A century ago this brilliant yellow gem, which is identical with the
ruby and sapphire in everything but color, was nearly as valuable as
they. Now it has no value worth mentioning as a jewel, and is chiefly
used for optical purposes and by clock-makers.
The
bluish-violet mineral hyacinth has been known for many years as an
inferior gem-stone. The name hyacinth is not altogether a good one,
although it has been applied by jewelers to all of the zircon gems.
Zirconium does not occur free in nature. As a mineral, zircon is found
chiefly in India and Ceylon. Zircon is essentially an Oriental gem. It
is found in the sand as grains.
Zircon
is much oftener met with in the bazaars of Ceylon than in the jewelry
shops of Fifth Avenue and the Rue de la Paix. The sixth of the seven
Moslem heavens is said to be composed of yellow jacinth, which is one
of the names for the gem zircon.
In
hardness zircon is 7.5, rather harder than quartz but not as hard as
topaz. It is therefore not altogether suitable as a ring stone, but
with a range of color that is highly attractive and an index of
refraction that enables them, when cut, to rival the diamond in
brilliancy. With all the strik-
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