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Large Oval Chrysoberyl Mounted in Cluster RIng
Cat's Eye Photo to Follow
Large Oval Chrysoberyl Mounted in Cluster RIng

Cat's Eye
True cat's eye is a variety of chrysoberyl, sometimes called cymophane, and as such is related to alexandrite.
It is a rare and valuable gemstone, which is often underrated as being a "semi-precious" stone.

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.
Other stones which show chatoyancy include sapphire and tourmaline.
Chatoyancy is related to asterism.

Cat's eye chrysoberyls are always cut as cabochons to show off their spectacular effect to it best.

Cat's eye chrysoberyl is green or yellow-green, yellow, or brown to yellow-brown.

Technical Information
Chemical Composition and NameBeAl2O4 - Beryllium Aluminium Oxide
Refractive Index1.742 - 1.749 to 1.750 - 1.757
Bi-refringence0.008 - 0.009
Other Optical PropertiesBiaxial
Optic SignPositive
Specific Gravity3.68 - 3.78
Crystalline SystemRhombic the Lowest Possible Price

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