The rings are beautiful, especially the last one!
I was going to say that I like your pictures. For the fact that you don't only use white backgrounds but also marble and leather and wood. The first black and white picture on wood is superb.
I just recently posted my photographing method in a jewelry forum, because there was a discussion also.
Unfortunately is it a german forum but here is the post in english:
First you need a surrounding / studio. I learned this from CAD rendering. The surrounding can be anything, but I prefer a white / grey one that is bright:
This gives good lighnting. For reflective surfaces, that jewelry has, just a room in the background always creates unwanted shades and reflections.
You can also experiment. If you take a dark surrounding with white highlights on it (imagine white squared that simulate windows), something like this might be the outcome:
The contrast is much higher.
Finally it is important to use the flash, at least that's my experience. No matter how good the lighting of the room is, without flashing light the pictures are always kind of washed and blured. However using a flash sometimes results in to much reflection and overexposure, especially for close ups. That is why this trick has worked very well for me:
I infact just stuck a piece of normal paper in front of the light. It is important that it has a parallel orientation to the light. Otherwise it might create an anoying shadow. Other than that it can really be that simple. Now the flashlight still goes through, but its smoother.
I hope you find the time to try these things out, if you want.
Regards
Leander