I work and live with a large of group of gemologists so I've found a few things out:
1) most of the books that say "this sign=this crystal" is bollox.
--however--
certain crystals do work better for certain tasks
example: quartz, raw or polished, is a grounder. Which is why most people feel most comfortable with it.
Amythist is a type of quartz and there fore holds simular propties.
2) the right crystal will call to you. You will find your match in crystals, I have dozens of them. I, how ever, only take them if they call to me or someone else through me, because oterwise they are meant for someone else.
For this reason I have some wire wrapped into jewelry which I switch wearing every so often.
I also keep a six set (of amythist and quartz) near where I sleep at all times so if anything goes wrong I can circle and shield up for the night and be un-molested.
have any questions? Contact me.
Want your own crystal?
If you talk to me and I get to know your personality, I might be able to match a few of you. no promises though.