Chrysoberyl is not one of the best known gemstones. Its rarest variety Alexandrite, however, is quite well known, although the number of people who have heard of Alexandrite is probably 100 times greater than the number who have ever seen one, and 1,000 times greater than the number who have ever owned one.
 

Cat's Eye Chrysoberyl is a translucent gem ranging in color from a honey yellow or honey brown to yellowish green to an apple green. It is known for its reflected light effect called "chatoyancy." This is achieved by cutting gems that have very small, parallel "silk" inclusions into cabochons. As the gem is rotated, it exhibits a distinct, silvery white line across its dome that seems to open and close like a cat's eye.

 

Fine Cat's Eye Chrysoberyl may be yellow, yellowish green, or golden brown. In the finest qualities, the gems will be semi-transparent and they will exhibit a sharp white eye. As you turn the gem around, the eye will move. The best Cat's Eye Chrysoberyl also exhibit a "milk and honey effect," when the gem is rotated, one side of the gem appears transparent, as the other side takes on a creamy appearance. In large Cat's Eye Chrysoberyl, the milk and honey effect is an important consideration in valuing the gem.