Chemical Formula BeAl2O4
Color Red, Green, Yellow, Orange, Brown, Pink, Gray, Black, Multicolored
Crystal System Orthorhombic
Refractive Index 1.744 – 1.755
SG 3.5 – 3.8
Transparency Transparent to translucent
Double Refraction .009
Cleavage 1,1 ; 3,2. Often exhibits parting along twinned crystals.
Mineral Class Chrysoberyl
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.
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.
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.Chrysoberyl gemstones are not treated or enhanced.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.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.
Chrysocolla is a gemstone with a beautiful sky blue to bluish-green color. Copper in its chemical structure is responsible for the bright attractive color. It is often multicolored with inclusions or veining of black and brown matrix material. Chrysocolla’s lack of widespread gem use is due to its low hardness and lack of durability. It is sometimes coated or admixed with harder Quartz, and these harder, more solid forms are better fit for gemstone use.
Chrysoberyl TREATMENTS AND ENHANCEMENTS