While surfing the web, I ran across an article about photographing jewelry. I won't give you instructions here, instead, I will let you go read the articles themselves.
I will say this though, the photography is excellent, and I'm a big fan of using glass on top of your background.
The first half of the article is here
The second half, which has my favorite pictures in it, is here,
I hope you find these useful and enjoyable. Good luck with your photography!