Take both to a jewelry store and have them do it. They probably won't charge.
The current New York Spot price is (per ounce): Platinum - $1431.00 Gold - $752.90 Palladium - $357.00 Silver - $13.46 The difference between white and yellow gold is roughly the same due to the gold content of equal carat amounts being equal (gold c...
Most gold plate will thin over time, but some go on for years, the fact it's white gold is no different to normal gold tho. It should go on for a good few years yet. Your friend sounds as if they maybe just wanted to make a point.