The diffuser box looks like a really great idea for solid, non-reflective objects.  I’ve just now tried to rig up a diffuser somewhat similar to your suggestion, but I just ended up with even more bad reflections.  8^(  Have you had success with your use of the diffuser and an engraved transparent sphere?  Is there some trick to it?

Oh, that gives me an idea – maybe I could infiltrate some kind of black stuff, like black yarn or cloth or something, into the ornament, thru the neck.  Hmmm, I’ll report back, but in the meantime any further input will be appreciated.