I just published this tool today. It lets you model most diamonds in
3D, loose or with simple tiffany style rings. You can compare 2
stones or rings at a time. Being 3D you can view, zoom, or pan from
any angle. It lets you pick the carat or mm sizes of the stone, as
well as the ring size, # of prongs, and stone height.
It's kind of neat because you can make all these changes on the fly.
It's at http://www.RingHunt.com
Let me know what you think of it. Is this useful to you?