 Quartz
that is formed not of one single crystal but finely grained
microcrystals is known as chalcedony. The variety of chalcedony
is even greater than transparent quartz varieties because it
includes cryptocrystalline quartz with patterns as well as a
wide range of solid colors. Agates
are banded, bloodstone has red
spots on a green ground, moss agate
has a vegetal pattern. Jasper sometimes looks like a
landscape painting. Another staple of the jewelry industry is
black onyx, chalcedony quartz which
owes its even black color to an ancient dyeing process that
is still used today. Carnelian (see image below), another
chalcedony valued in the ancient world, has a vivid brownish
orange color and clear translucency that makes it popular for
signet rings and seals.
Chrysoprase (see image
above), a bright apple green translucent chalcedony, is the
most valued. It was a particular favorite of Frederick The
Great of Prussia, who loved its bright green color. It can
be seen today decorating many buildings in beautiful Prague,
including the Chapel of St Wencelas. Chrysoprase is found
today mostly in Australia. Unlike most other green stones,
which owe their color to chromium or vanadium, chrysoprase
derives its color from nickel. Its bright even color and texture
lends itself well to beads, cabochons, and carvings.
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