White gold jewelry offers an elegant and unique difference from similar jewelry in sterling silver or platinum. In fact, white gold was initially promoted as an alternative to platinum jewelry, and it doesn’t take long to realize there are many reasons white gold is the better choice. In this article we’ll look at how yellow gold is made to appear silvery white, the properties this gives, and the ranges of gold content found in white gold.
White gold resists tarnish better than yellow gold of the same karat and it has a greater hardness.
White gold alloys initially contained 80% pure gold (just over 19k!), although white gold alloys can span the karat purity spectrum from 10k (41.7% pure) all the way past 18k and to 19.4k (80.8% pure) – the highest karat purity possible for white gold.
It is made by taking a base-metal alloy (usually copper, nickel, and zinc) and mixing it with pure yellow gold in proportion to the desired karat purity. The percentage of copper used, in relation to the amount of nickel and zinc, can be adjusted somewhat but must fall within a narrow band of “composition limits” in order to achieve white gold. In general, the lower karat purities (like 10k white gold) will have more copper and less nickel while higher karat purities (like 18k white gold) will have significantly more nickel than copper.
This sliding scale of base-metal composition percentages in relation to the karat purity of white gold also has an effect on the metal properties, most notably: hardness and color.
Nickel is a very hard metal, much more so than copper. So the more nickel contained in the base-metal alloy portion of white gold, the harder the resulting alloy will be. This is quite noticeable on higher purities of white gold (18k and above) since the base-alloy portion contains at least 70% nickel at this level.
Platinum and Palladium in White Gold
Especially in vintage and older pieces of jewelry, it was quite common to use palladium or platinum in place of nickel in white gold. This, again, not only changes the properties somewhat, but should also be considered if you buy and sell scrap gold or are interested in precious metal recovery at all. Finding older pieces of solid white gold with platinum as a secondary metal can be very profitable indeed!
Hope this gives you a good primer on white gold, with some thirst to learn more. Thanks for reading!