White gold is generally plated with a fine layer of rhodium (a platinum group metal) to achieve a bright white finish. This rhodium layer can wear off over time, exposing the darker grey colour of the gold underneath. Replating your white gold jewellery is optional, however you may want to factor this into its cost over time. Platinum may be an option to consider if you're after a bright white metal that doesn’t need to be rhodium plated. Read more about the difference between platinum and white gold.