Here's an example that might benefit from more "negative space." That means not cropping so tightly. Look at some of the results of the negative space challenges for some ideas. Here's one example:
Your image doesn't have the same vibrant background, but do you see how the large space away from the subject gives some interest?
The other main issue here is focus. You want the marble to be sharp and the background to be soft.
You also want to avoid the harsh "spotlight" effect of the lamp. My first entry suffered from the same problem.
Search Google for "light tent" to learn some things about lighting. I've been experimenting with many ways to diffuse lights, like pillowcases, tissue paper, and even my hands.
Putting the light to the side will not only hide its reflection but also create some drama with shadows. Long shadows coming out the side are more interesting than short ones directly behind. They also look deliberate.
This has potential ... I like the idea. It seems sorta out of focus. The lighting would be more effective from the side or from the back to look more planet-like also.