White gold, especially in some jewelry pieces, may turn yellow over time when its rhodium plating gradually wears off. Rhodium plating is the preferred plating method used on most white gold rings because it is a pure white metal. This property of rhodium gives white gold jewelry a much whiter appearance and a more brilliant sheen.
Pure gold has a very yellow shade and regardless of the proportions that it is alloyed with other metals such as zinc and nickel, it will still exhibit a yellowish hue. Without its rhodium plating, white gold still has a yellow tone.
Plating is a method used to coat a conductive surface with metal using electricity, chemicals or a combination of both. In the jewelry industry, it is often used to give jewelry pieces a silver or gold finish.
When white gold jewelry starts to turn yellow, it does not necessarily mean that the piece of jewelry is fake. Rhodium plating gives white gold an extremely thin coat. As this thin coat degrades and wears off, it slowly exposes the real white gold underneath, which still has a yellow tone. The good news is that jewelers can easily restore the white sheen on white gold jewelry pieces that have turned by simply re-plating it with rhodium at an affordable price.