Many photographers also use something called a light box, which you can either purchase from any place that sells camera equipment or even make your own. The box helps to trap the light around the jewelry as you are taking the picture. Also consider investing in some special equipment such as a tripod to help keep the camera steady and and a macro lens to help show the detail of your jewelry pieces.
However, if you aren't ready to dive into a lot of photography equipment, another option is a simple digital camera that has telephoto capability. I have a Kodak EasyShare C913 camera that was only $100 at my local discount store, and that little camera actually does a pretty decent job.
So, those are some tips to think about as you experiment with the best method for taking your own jewelry pictures. The only issue I would continue to stress is making sure you have plenty of light, especially if your jewelry includes a lot of metal. Without the proper lighting, you just can't get the visual image you need to help showcase your jewelry creations.
