This stone is not a type of beryl in spite of its name. The Tibetan has adopted the Prakrit form of its name: ke ke ru. It is the third hardest gemstone. It comes in three main varieties: the eponymous yellow or green chrysoberyl; cat’s eye (cymophane), which is light green or yellow with a band of light, resembling a cat’s eye; and the third form, alexandrite, which can change color from red to green to yellow according to the light. All three kinds have been mined since ancient times, in Sri Lanka in particular.

A stone sometimes identified as cat’s eye.