cha·toy·ant 
(shə-toiənt)
(shə-toiənt)adj.
Having a changeable luster.
n.
A chatoyant stone or gemstone, such as the cat's-eye.
[French, present participle of chatoyer, to shimmer like cats' eyes, from chat, cat, from Vulgar Latin *cattus, perhaps of African origin.]
cha·toyan·cy n.
chatoyantcat's-eye quartz