Kountryb: One of the first issues I see is lighting. If your using the camera flash, you can try to set up another light - going in the opposite direction of the camera flash - this should help offset and minimize shadows, and make the subject a bit brighter. Otherwise (if not using the camera flash) you might want to set up several lights around your subject, from a couple of different angles. One of the first things I learned about photography is to pay attention to the light - your really photographing light, and how the subject is lit makes all the difference.
Another thing is focus. If your not already using one, get yourself an inexpensive tripod. I rarely take (commercial) photographs without one. (Pictures of my 3-year old OTOH - even a tripod wouldn't help me!

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I hope this helps - you do make nice jewelry!
~Val