Is it true that gem quality man made diamonds are possible? How can they tell the difference between an industrial grade and gem quality and how do they grade them? I think the clearer the better and that the defects have to do with elements/compounds other than carbon. Any more info would be cool. Does diamond have the highest index of light refraction? Thats what gives it its bling-bling right, the fact that the light just keeps bouncing around in there? And what is cubic zirconium, like is it also made of carbon but a different crystal structure, and how does its light refracting ability and clarity compare to the real thing?