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Horology 101 - white gold



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ulackfocus

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Published on 08-11-2008 05:08 PM

Number of Views: 1156

White gold was developed in the 1920's as a platinum substitute. Adding white metals to gold will lighten it's color, and some metals have a stronger bleaching effect than others. Nickel, iron, chromium, palladium and platinum are the most effective whiteners. Zinc and silver work almost as well. There is no set standard in the industry to define white gold's color, and the only regulation about white gold at all came January 20, 2000 in Europe pertaining to the use of nickel. Nickel can bleed from white gold and cause an allergic reaction in some people. European Union countries are trying to eventually eliminate the use of it in all jewelry. In the US there is legislation to label nickel alloys with a health advisory. Alternative options like manganese, iron and chromium have been experimented with but unfortunately these metals make white gold alloys that are difficult to cast and are much more likely to crack or tarnish. Palladium and platinum make the whitest color alloys and are easy to work with, but are cost prohibitive - they cost more than gold itself per troy ounce. Another drawback is they have a higher melting point which makes casting a bit more difficult and less energy efficient and therefore more expensive. There are many formulas for white gold; here are just a few:

18K Nickel white gold

75% gold + 2.2% copper + 17.3% nickel + 5.5% zinc

14K Nickel white gold

58.5% gold + 24% silver + 10% nickel + 7.5% zinc

18K Palladium white gold

75% gold + 15% palladium + 10% silver

14K Palladium white gold

58.5% gold + 5% palladium + 32.5% silver + 3% copper + 1% zinc

There are even alloys that use both nickel and palladium. No matter what elements are used in white gold all but the best alloys have a dull finish. To overcome this, rhodium plating is used. Once again there is no standard on the thickness of the plating nor is it mandatory that the consumer even be told that electroplating is used. Here's an earring with some of the plating removed to expose the mediocre white gold underneath:

IMG_2166-1-1.jpg


The World Gold Council in London has proposed grading white gold into categories. 3 options are Premium, Standard, and Off-white. Premium has the best white color and would not require rhodium plating, but would be very expensive due to the amount of palladium used. Standard would be a slightly lesser grade and rhodium plating would be optional. Off-white would necessitate rhodium plating.


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Horology 101 - white gold
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ulackfocus
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