While I was working at my "day job' today, I helped a woman who had 2 very large beautiful rings on. One ring had the largest, clearest peridot stone I had ever seen. The other had a large clear multi-faceted cabochon, looked like it could have been crystal, on top of a flat piece of abalone. All you could see was the clear stone until you looked into the stone, and then the colors changed like a rainbow moonstone.
Very beautiful, and very good idea.
Just wanted to share that idea. Maybe someone else can use it.