200px|thumb|right| Rhodium plated white gold wedding ring
White gold is an alloy of gold and at least one white metal, usually nickel or palladium. Like yellow gold, the purity of white gold is given in carats (karats). It is often used in jewellery.
A common white gold formulation consists of 90% gold and 10% nickel by mass. Copper can be added to increase malleability.
While some higher-quality white gold alloys retain their shine and lustre, most will be coated with a very thin layer of rhodium. This gives the naturally duller white gold a shine comparable to that of platinum or silver, although the rhodium may wear off over time.
Skin irritation
The nickel used in some white gold alloys can cause an allergic reaction when worn over long periods (also notably on some wristwatch casings). This reaction, typically a minor skin rash from nickel dermatitis, occurs in about one out of eight people; because of this, many countries do not use nickel in their white gold formulations.
White gold alloys made without nickel are less likely to be allergenic.
See also
- Colored gold
- List of alloys