PRECIOUS STONES 109
occurs with garnet, apatite, and tourmaline, in New York State, at Saratoga and elsewhere.
The
variety known as alexandrite ranks among the " precious" stones. It is
light to dark olive-green by day and purplish or reddish, rarely
ruby-red, by artificial light. It was named after Alexander II., Czar
of Russia, as it carries the Russian military colors, red and green,
and was discovered on his birthday in his dominion in 1830 in the
emerald-mine at Tokowoia. This variety is often nearly opaque, and when
transparent is usually so flawy that it cannot be cut to gems. Ceylon
furnishes most of the alexandrite marketed at present, as the material
from that country is structurally more perfect and easier of
manipulation by the cutter.
Mr.
Edwin W. Streeter mentions in his book on precious stones that in the
course of his experience he had seen several specimens which, cut en cabochon, showed a perfect cat's-eye line.
The
cat's-eye is another variety of chrysoberyl. This singular stone
contains fine striations caused by regular layers of infinitesimal
cavities, which produce, when properly cut en cabochon, if the
structural arrangement is perfect, a narrow and distinct line of light
over the dome from one edge of the stone to the other. It is regarded
by the natives of the East Indies, the Cingalese especially, with
superstitious veneration, and they will seldom part with one that has
come into their possession. It is rarely found outside of Ceylon,
though occasional specimens are found in China.
The
common color is gray, but it ranges through all shades of honey-brown
to one that is almost black, and from the palest apple-green to a deep
olive. The light-line, when the stone is held squarely before the eye,
should cross the centre of the dome and be narrow and well defined. In
the finest the edges of the ray appear more brilliant than the centre.
The chatoyant line is usually white; rarely, bright yellow.
