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The Gemstone Chrysoberyl

Chrysoberyl is a hard, tough, and durable gem. Although lacking the fire of other gemstones, Chrysoberyl in its various forms can be quite valuable. Most Chrysoberyl gems are yellow, though some are brown, green, or orange. Chrysoberyl is best known for its important varieties Alexandrite and Cat's Eye. Alexandrite is a rare and expensive form that exhibits different colors in natural and artificial light. Cat's Eye is Chrysoberyl that is polished into a cabochon and highly chatoyant, displaying a sharp line of light through the center of the stone.

Color

Red, Green, Yellow, Orange, Brown, Pink, Gray, Black, Multicolored

Hardness

8.5

Chemical Formula

BeAl₂O₄

Mineral Class

Chrysoberyl

Additional Properties

Crystal System
Orthorhombic

Refractive Index
1.744 - 1.755

Double Refraction
.009

Transparency
Transparent to translucent

SG
3.5 - 3.8

Luster
Vitreous

Cleavage 1,1 ; 3,2. Often exhibits parting along twinned crystals.

All About

Chrysoberyl is most often a lightly colored gemstone, though increased color saturation will increase its value. Chrysoberyl gemstones are often free of flaws, though stones larger than several carats are uncommon. With a hardness of 8½, Chrysoberyl is also one of the hardest gemstones.

The cat's eye effect exhibited on the Cat's eye variety is caused by is caused by microscopic needle-like fiber inclusions that cause the light to band together in a thin streak. The term "Cat's eye" when used alone without any gemstone name prefix will always refers to Chrysoberyl Cat's eye, which is the most famous and valuable of the cat's eye gemstones. All cat's eye gemstones other than Chrysoberyl must be designated by their gemstone name, such as "Tourmaline Cat's eye", or Cat's Eye Tourmaline.

Uses

All colors of transparent Chrysoberyl can be faceted into gemstones. Despite its appealing and valuable nature, Chrysoberyl is not extensively used in jewelry. The most common colors for Chrysoberyl jewelry are yellow, greenish-yellow, and brownish-yellow. Cat's Eye is polished into cabochons, and usually has a yellow-brown, greenish-brown, greenish-gray, or gray color. Alexandrite is used as rare and exquisite jewelry piece, and most often faceted into round and cushion cuts that are used in rings and pendants.

Other Names

Chrysolite

Varieties

Alexandrite - Rare and well-known variety of Chrysoberyl that exhibits a different color in artificial and natural light.
Cat's Eye - Chrysoberyl that exhibits a cat's eye effect, in that it reflects a long thin wave of light across a polished cabochon gemstone. Although the term Cat's eye can be applied to other gemstones with this name, the Chrysoberyl form is the most well-known.
Cymophane - Polished Chrysoberyl exhibiting a floating light reflection known as a cymophane effect.

Treatments & Enhancements

Chrysoberyl gemstones are not treated or enhanced.

Chrysoberyl Sources

The most significant Chrysoberyl deposits are in Brazil, but other important deposits are in Australia, Madagascar, Zimbabwe, Myanmar (Burma), and Russia. Cat's eye is found in Brazil, India, China, Sri Lanka, and Zimbabwe, and Alexandrite comes from Brazil, Russia, Madagascar, Sri Lanka and Tanzania.

Similar Gemstones

Topaz, Heliodor, Peridot, Yellow Sapphire, Citrine, and Zircon may resemble Chrysoberyl. Chrysoberyl Cat's eye can be distinguished from other cat's eye gemstone by its greater hardness.