The Meaning of Chatoyant
A rock or mineral that's chatoyant exhibits a distinctive optical phenomenon caused either by the fibrous structure of the mineral or by its fibrous inclusions or cavities which reflect light from within the stone. In some minerals the effect gives the impression that colours and markings are moving around whilst in others the reflection forms a line of light in one specific section.
In order to see chatoyance in a gemstone it must be gently tilted and moved around in good light. The phenomenon can vary significantly from one stone to the next.
The best known chatoyant gemstones are tigers eye and chrysoberyl also known as cats eye although it can also be seen in several other rocks and minerals. The word chatoyant originates from the French word for cat's eye.