Chatoyant

You've got to love Michael Quinion's World Wide Words:

Chatoyant /S@'tOI@nt/
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Having a changeable, varying lustre or colour.

No two dictionaries seem to entirely agree on the current meaning
of the word. Some mention only the bright lustre of a gem caused by
reflections from within the stone, because the word now most often
appears in discussions by gemologists; other dictionaries include
the sheen of a bird's plumage or the changing colours and texture
of a material such as silk.

All agree, however, that the source of the expression is the gleam
of a cat's eyes in the dark. The direct source is the eighteenth-
century French verb "chatoyer", to shine like a cat's eyes. Its
French connections remain strong enough that it is still sometimes
said as though it were French (roughly "cha-twai-yan").

Many examples in English literature refer to shining eyes, as in
The Insidious Dr Fu-Manchu, by Sax Rohmer, of 1913: "I managed to
move sufficiently to see at the top, as I fired up the stairs, the
yellow face of Dr. Fu-Manchu, to see the gleaming, chatoyant eyes,
greenly terrible, as they sought to pierce the gloom."