There are several bands called Amethyst.
1. A trance / progressive house duo. http://www.discogs.com/artist/Amethyst
2. A Melodic Death / Melodic Black Metal band from the Netherlands.
3. Heavy / Progressive Metal band from Australia.
4. A Thrash Metal band from Italy.
5. A Progressive Metal band from Sweden.
6. A Progressive Metal band from the USA.
7. A Power Metal band from Canada.
8. A Power / Thrash Metal band from the USA.
9. A defunct Pop Rock band from Youngstown, OH, USA.