How can I tell if my quartz is rose or amethyst?

I has a chunk of quartz and I'd like to know exactly what kind it is. If you want to know the back story, i'm building a Tesla coil, and wanted to know how the resonant frequency of the crystal in the electromagnetic field would effect me (crystal healing, I believe). Apparently, the frequencies of these quartz crystals are different (I just umed that being quartz and of nearly the same color they'd be pretty much the same) oh well, help?