Rhodium, among other uses, is used in some catalytic converters and is used as a coating (or electroplate) on white gold and platinum jewelry.
It is shinier than platinum or white gold, looking a bit like polished chrome and reflecting 80-85% of light instead of 60-65% with platinum, which looks greyer next to Rh.
Rh is also tougher than gold or platinum. I believe it alternates with rhenium for most expensive metal.
Yeah, $440 per ounce 5 years ago, $10,000 now. And was even cheaper long ago.
Hmm, now I'm wondering how much Rh my wifes ring has...