They are not specific to the RS500.
Same wheel on the standard Sierra RS Cosworth.


You should be able to find loads of decent pictures on the net. Sorry I don't know the codes of the colours or names but the inside of the spokes was a light grey and the face diamond cut.
Wheels refurbed always tended to be a slightly darker grey for some reason, don't know why. Picture is of my spare that had been refurbed, but you get the idea.