Hi tj_925,
Welcome to the Q&A board!
Using the zoom lens is really not the best way to get detailed shots of jewelry, especially if you're using the long end of the telephoto lens and standing too close. If you back up, you'll probably get better focused shots, then simply crop when you edit to get the close up look.
However, I really don't recommend you use the zoom. You will get
much more detailed photos if you use Macro or Super Macro mode using a tripod. You don't have to spend a lot but just make sure the tripod is sturdy enough so it won't topple over when placing the S2 on it. For close-up shots, get a tripod that will allow you to position the camera horizontally and vertically.
Bright but soft, diffused lighting is the key to getting good shots of jewelry. Here are some tips on taking close ups of small items:
http://www.digicamhelp.com/auction-photography/index.htmI took photos of jewelry using the suggestions outlined in the above article. I did spruce them up a bit when editing:
http://bykari.com/gallery/index.htmPlease let us know if you have further questions.
Related reading - Tripodshttp://www.digicamhelp.com/tripods/