Cat's Eye, the true variety, is a variety of chrysoberyl, sometimes called cymophane,
and as such is related to alexandrite.
Fine Cat's Eye is a rare and valuable gemstone, which is often underrated as being a
"semi-precious" stone.
Chatoyancy
Chatoyancy or chatoyance, literally from French means cat's eye. It is the effect seen best
in this variety of chrysoberyl, but also found in a few other gemstones. The effect is a
strongly banded one caused by tube-like or needle-like crystals running along the length of
the stone.
Cutting Style
Cat's eye chrysoberyls are always cut as cabochons to show off their spectacular effect to it
best.
Coloration
Cat's eye chrysoberyl is green or yellow-green, yellow, or brown to yellow-brown.
Technical Characteristics
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Chemical Composition:
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BeAl2O4 - Beryllium Aluminium Oxide
|
|
Hardness:
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8.5
|
|
Specific Gravity:
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3.68 - 3.78
|
|
Refractive Index (R.I.):
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1.742 - 1.749 to 1.750 - 1.757
|
|
Bi-refringence:
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0.008 - 0.009
|
|
Optic Sign:
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Positive
|
|
Optical Character:
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Biaxial
|
|
Crystal Structure:
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Rhombic
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