In the following picture you can see part of the ring in the frame, but I can't deliver you any technical exposure details right now (as with all the photos that follow, as I have taken them from my "blog" - propaganda link in signature).
In the next picture I held the flash half a meter away, probably set to half its strength.
The next one is nothing is nothing special either, but I like how it looks a bit like sunlight.
This one was the most surprising, as it was a filled ashtray (to the rim) and I placed the ring under the 1cm thick glass ashtray.
Those are just some radishes, with the light from behind.