Capturing luster

I have been trying to play with the lighting source, angles, background colors and post processing to try and best capture the luster of some of my collection. Any advise would be more than welcome.

First 2 pics are of Hematite with a quartz crystal.
The other is what I am told is a type of slab garnet. I chose this pic as it shows a difference in how the light hits in different areas and fractures.