I'd look for blogs that mention photographing rhinestones. (I used to be in to rhinestone brooches and seem remember comments about photographing them.)
Most of the time, it's about the lighting and the direction of the lighting I think.
I found these links, but just scanned them. Maybe they will be helpful.
http://www.tabletopstudio.com/docume...hotography.htm
https://photo.stackexchange.com/ques...parkly-objects
https://www.cambridgeincolour.com/forums/thread3578.htm
bkay