Now question. If you are using a lightdome such as the one in I13's IDL studio could that count as an environment to bounce the light back for the refractions so as to get the same effects without having to have other objects in the scene, so it can render out a base image to use as a png resource for a realistic gem, so when it is saved, it won't have to be edited in gimp or photoshop to remove say the counter tile like it is in your scene. This might be a dumb question but if I set up the scene as you have, then remove it from being viewed in the camera during raytracing would it give the same effect?

I often do this type of rendering for things I create for tubes, but haven't really needed to do anything more than basic setup and rendering for character pngs. I am new with use of refractions, but am interested in doing more with it.