am·e·thyst 
(ămə-thĭst)
(ămə-thĭst)n.
1. A purple or violet form of transparent quartz used as a gemstone.
2. A purple variety of corundum used as a gemstone.
3. A moderate purple to grayish reddish purple.
[Middle English amatist, from Old French, from Latin amethystus, from Greek amethustos, not drunk or intoxicating, remedy for intoxication, amethyst : a-, not; see A-1 + methuskein, to intoxicate (from methuein, to be drunk, from methu, wine; see medhu- in the Appendix of Indo-European roots).]
am′e·thystine (-thĭstĭn, -tīn′) adj.