Satin Black
Gloss Diamond Silver
Fluro! Seriously though, the silver looks much better. Since they aren't very concave, the gold just looks kind of flat IMO. I think it was @Caffeine Fiend who had some rx8 rims powder-coated in a gunmetal silver which looked great.
Yeah the black is a little... ghetto. Haha.
Here we go. Wasn't gunmetal but 'shadow chrome' http://www.ozmpsclub.com/forum/showpost.php?p=217376
2005 Mazda 6 MPS NZ New in Graphite Silver with Full Leather Interior
Jamex Super Low Springs | BBS RX-239 18x8 40p | Bose/JVC Bluetooth Unit Piggyback
Presumably you could just powder coat or paint it in a silver and maybe vary the clear coat to get it glossy or flat?
I think the way caffeine fiend did it you start with a darker base and add as many coats of silver as you like to get the right shade, but still keeping the 'depth' of colour.
I think I'd get mine professionally done as I don't trust myself with a spraygun haha. I'll see what my painter recommends.
Silver