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XXIV
SIMILAR STONES AND HOW TO DISTINGUISH
THEM
1. Cat's-Eye; Quartz Cat's-Eye; Crocidolite Cat's-Eye
The Oriental
cat's-eye, a variety of chrysoberyl, and third in the scale of
hardness, being 8.5, has a natural imitation in the quartz cat's-eye.
The latter is softer (7), and lacks both the lustre and mellow coloring
of the Oriental. The specific gravity is also 2.65 as against the 3.65
to 3.75 of the chrysoberyl.
Crocidolite,
or tiger-eye, is also cut and artificially colored to imitate
cat's-eye. It is much softer, has a silky lustre, and the chatoyant
light is neither sharp nor concentrated.
2. Chrysoberyl; Chrysolite
In
the yellow and greenish-yellow colors of these stones there is little
difference for the eye to distinguish. Except in unusually fine
specimens, the latter has a somewhat greasy lustre, compared with the
former, which looks sharper and harder, though many are not perfectly
transparent, inclining somewhat to a cats'-eye chatoyancy. As the
dichroism is not very decided in either, the only sure test in case of
doubt is by hardness and specific gravity.
Hardness. Specific Gravity.
Chrysoberyl.........................8.5 3.65 to 3.75
Chrysolite..........................6.5 to 7 3.34 to 3.37
3. Ruby and Spinel
These stones sometimes approach each other very closely in general appearance, although the red of the ruby, when it 184
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