…sorta. I’m also on a ring kick for some ungodly reason. Anyhow.
K
You could probably use Yafray for that it’ll look better with it’s ability to make caustics.
The materials look fine even if I’d personally set the Hard for the Spec a little more harder.
It seems that you use some sort of AngMap, do you? Reflections on the rings are a bitt off, because the rings are in a room and the reflections seem to be of a sky. Not a big deal, though, the pic is nice.
I’m not sure, but I think Caustics only effect translucent objects? Since these are metalic, I don’t think caustics would effect it much… mabey I’m wrong though. I agree with olivS that the gold and silver rings seem a bit soft, but I think the bronze looks really good, mabey harden it up just a little.
Overall, nice piece! I’m a reflections guy so I think it would be fun to mabey have an environment map for the rings, and a little reflection of the rings off the tray shelf their in 
but thats just me.
Caustics can occur from a highly reflective surface as well. If you had a concave mirror, light will get focused at a certain point after reflection.
If image didn’t work, try clicking following link:
[Edit] The image is from Henrik Wann Jensen’s site; the guy who wrote up the theory on photon mapping for caustics.
very nice dude , i hope i dont get bronze if i compete 
ill get gold!!!