The Collaborative International Dictionary of English v.0.48:

Cat's-eye \Cat's"-eye`\ (k[a^]ts"[imac]`), n. (Min.)
   A variety of quartz or chalcedony, exhibiting opalescent
   reflections from within, like the eye of a cat. The name is
   given to other gems affording like effects, esp. the
   chrysoberyl.
   [1913 Webster]