In mineral terms the difference between chatoyant and cymophane

is that chatoyant is a hard stone, such as the cat's-eye, which presents on a polished surface, and in the interior, an undulating or wavy light while cymophane is a translucent yellowish chatoyant chrysoberyl.

As an adjective chatoyant

is having a certain optical reflectance effect, which can be likened to the sheen of a spool of silk.