White gold
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White gold refers to an alloy of gold and other white metals such as silver, palladium, or nickel. The natural color of white gold is light gray, so jewelry made of white gold is typically coated in highly reflective rhodium (sometimes coated in platinum and palladium), adding a more brilliant shine. Palladium and silver alloys are of higher quality than nickel and are sometimes not coated with rhodium. The purpose of plating is to add luster to grayer jewlery, as well as to prevent oxidation of some of the metals found in the alloys. White gold is not platinum, but is used as a cheaper alternative, usually costing one-third as much as platinum.
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History
At the turn of the 20th century, a relatively unknown metal called platinum was being combined with diamonds by some jewelers. However, platinum was very expensive. White gold alloys were developed in the 1920s as a less expensive alternative to platinum. To meet the growing demand, several different alloys based on gold-nickel-palladium, in different combinations, became commercially available. During WWII, the use of platinum and nickel for non-war related applications was prohibited. As a result, palladium based white gold alloys became the only choice for consumers in the U.S. In addition to higher costs, white gold jewelry based on palladium alloys are denser and heavier than nickel based alloys. They are also not as white in color. After the war, lower cost nickel based white gold quickly once again became the dominant choice of the jewelry industry worldwide.
Health risks
Some people (about 12.5%) are sensitive or allergic to white gold. This occurs because of reaction to nickel found in some alloys of white gold. Reactions are mild and only involve rashes on the skin.
External links
- Nickel Gets Under Your Skin (http://www.gold.org/discover/sci_indu/GTech/2000_28/roy.pdf) (PDF, 246 KB)
- The European Directive on Nickel in Jewelery: Update (http://www.gold.org/discover/sci_indu/GTech/2000_29/update29.pdf) (PDF, 24 KB)
Care and maintenance
Typically, white gold is plated with only a layer of Rhodium 0.05 to 0.5 micrometres thick. Because of this thin plating, cracks will form causing oxides to form. This will weaken the Rhodium coating even more. A good idea is to plate with about 2.0 micrometres of Rhodium, for longer lasting and more durable jewlery. Replating can be done at your local jeweler.
External links
- White Gold (http://www.gold.org/jewellery/technology/colours/white.html) - This is a very good site provided by the World Gold Council.
- Platinum v. White Gold (http://www.ultimatewedding.com/articles/get.php?action=getarticle&articleid=199)de:Weißgold
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Categories: Gold | Alloys