Those are some really neat stones. Lighting's pretty harsh, try more of them and dimmer/less direct maybe? (I'm not going to pretend to be an expert) Velvet-like material works well as a more solid, light-absorbing background.
Subject and composition don't hold my interest. I think if you could darken the background more so it went away. Then with lighting get some reflections going on the nuggets and possibly boost the contrast. Then it would hold my interest better. Sorry just an opinion.