Hardly a day goes by in the Etsy Forum without someone asking "how do I photograph my...?" or "what's wrong with my pictures?" Unfortunately, "bad" pictures often have a lot of issues that are not addressed clearly in the forum answers.
Do not despair! There is hope! A while back I posted my #1 photography tip: use your light tent in full sun. When that is not feasible, I use a partly sunny window with lights on the side and top:
My # 2 photography tip is to read your camera manual. You can download it online if you can't find the original. Now that some of that is Greek to you, go directly to tip # 3.
My # 3 photography tip is to read this EXCELLENT tutorial written by a photographer who also sells jewelry online. She condenses what you need to know about your camera, lighting and exposure for getting good jewelry photos. She also gives very good explanations of what usually goes wrong and how to correct the problems you'll encounter.
Remember that the camera is just another tool and you can learn how to get the results you want.