My rings seven years old, white gold; once Iv got them rhodium plated, they dont discolour but rather the white gold wears off showing the yellow gold underneath. €30 a ring. However husbands wears very badly, depends on what you do/how much wear.
Platinum more expensive but heard it scratches easily and rings of same age iv seen looks a very heavy grey.
gold is out of fashion but have seen some lately appear but most people first thought is they spent less...