Cat's Eye Translucent yellowish chatoyant chrysoberyl is called cymophane or cat's eye. Gems lacking the silky inclusions required to produce the cat's eye effect are usually faceted. An alexandrite cat's eye is a chrysoberyl cat's eye that changes color.
Amber is fossilized tree resin (not sap), which has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects. The abnormal development of resin in living trees (succinosis) can result in the formation of amber. Inclusions of other substances can cause amber to have an unexpected color. Pyrites may give a bluish color. Bony amber owes its cloudy opacity to numerous tiny bubbles inside the resin.