There are generally two varieties of cat’s eye the alexandrite cat?s-eye and the chrysoberyl cat’s-eye, which is very popular in the Far East, particularly in Japan. The ideal colours of the chrysoberyl cat’s-eye are yellowish-brown, which is called the honey colour, and the yellow-green, which is called the apple green colour. A very good cat’s eye, apart from being of ideal colour, should have a high degree of transparency and a well-defined unbroken ray. It should be free from any distracting inclusions visible to the unaided eye. The chrysoberyl cat’s-eye is one of the most beautiful gemstones because of the chatoyancy or the eye effect.
A translucent variety of chrysoberyl (beryllium aluminum oxide) which exhibits a silvery white line across the stone. This moves as the stone, the light source or the observer moves and may appear to open and close like an eye.
The finest quality has a sharp eye that appears to open and close as the stone is rotated, and exhibits a strong “milk and honey” effect (stone on one side of the eye appears lighter than the other). These colours switch as the stone or [light source is moved. The most highly prized body colours are greenish-yellow and brownish-yellow (honey colour).