Chrysoberyl is not one of the best known gemstones. However, its rarest variety, alexandrite,
is very well known. It may sound strange, but the number of people who have heard of
alexandrite is probably 1000 times greater than the number who have ever seen one, and 10,000
times greater than the number who have ever owned one.
Chrysoberyl is composed of Beryllium Aluminium Oxide, is harder than topaz, and includes a
variety known as cat's eye, in addition to alexandrite just mentioned.
Coloration
Most chrysoberyl is green or yellow-green (as pictured above), but can also be brown. The rare
alexandrite shows a color change from green to red, and cat's eye has a strongly banded
appearance which is well described by its name, and is also usually green or yellow-green.
Early Fashion
Chrysoberyl was very popular in Victorian and Edwardian times, when it was often inaccurately
called chrysolite. It is possible that supply was more plentiful around that period, certainly
it is not as frequently seen today.
Technical Characteristics
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Chemical Composition:
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BeAl2O4 - Beryllium Aluminium Oxide
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Hardness:
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8.5
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Specific Gravity:
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3.68 - 3.78
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Refractive Index (R.I.):
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1.742 - 1.757
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Bi-refringence:
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0.008 - 0.009
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Optic Sign:
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Positive
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Optical Character:
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Biaxial
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Crystal Structure:
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Rhombic
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