Hi,
I checked out the photos and you are on the right track! One thing you'll want to do it shoot from over the jewelery, a bit more and if possible use a tripod. A tripod will help eliminate camera shake. Also, whatever lightsource you use, be sure to let your camera know that. The usual settings are:
Daylight
Fluorescent
Incandescent
Shade
Auto
Each of the light sources above has it own color. Light from a regualr light bulb is usually yellowish, fluorescent light is greenish, and daylight is a nice crisp white. I think shade is blue. In any event you'll want to tell your camera,"Hey I'm shooting with yellow light, please act as if its white." If you do not do this your jewelry will have the color of the light source which in some cases is undesirable.
Daylight makes great light for taking photos of jewelry. If your camera has manual settings use these:
F/16 @125 ISO 100
Sandra