noun, plural cat's eyes, cat's-eyes.

What is a Cateye?

cat's-eye, any of several gemstones that, when cut en cabochon (in convex form, highly polished), display a luminous band reminiscent of the eye of a cat; this particular quality is termed chatoyancy. ... Corundum cat's-eye is an imperfect star sapphire or ruby in which the star is reduced to a luminous zone.

How do you spell Chatoyancy?

In gemology, chatoyancy (/ʃəˈtɔɪ. ənsi/ shə-TOY-ən-see), or chatoyance or cat's eye effect, is an optical reflectance effect seen in certain gemstones, woods, and carbon fibre.