Lately, With the progress of Cycles, different new metal materials have been published. This inspired me to these 3 rings.
Thanks for gold and silver go to elbrujodelatribu (http://www.blendswap.com/blends/view/38983 and http://www.blendswap.com/blends/view/69793), for platinum to BroadStu (http://www.blendswap.com/blends/view/48688).
Think of the ornaments as very thin ceramics. The 3 textures were made with GIMP. The rings have slightly different topology. As there are 3 ornaments combination can produce 9 different rings (That's why the rings and ornaments are still separated.) Also the number of the subs is freely eligible.
Rendertime for 1000 samples is 72min (on a notebook with win performance 4.7).
Fortunately, there is a way to fix it. Once you'd corrected your model use "Manage Files" to reupload de new blend and the new sample image (deleting the old one), as long as you wish to do that. Very nice your work. Regards.
I have only made a simple compositing: less brilliance, more contrast, i.e. here is now the new blend and picture. Sorry for any inconvenience.
As there was comment and good advice at another site which led to important improvements I update once more: both outside and inside of the rings are now clean, i.e. without horizontal breaks of reflection.
If anybody thinks that I should have waited until the blend is really finished he is fully right.
Unfortunately I realized only after upload that the picture is too bright and has not enough contrast...