Why does white gold turn yello?
White gold is an alloy of gold and either nickel or palladium. Nickel is hard and is used in rings where palladium is soft and is used for gemstone settings; either way the real gold has been mixed with these to get the silver/white colour. If the gold is only lightly plated with the alloy, it turns yellow soon as it wears off much quicker than it would have done if it was entirely an alloy.