The popularity of white gold has us all looking to the most perplexing gold we use. Perplexing a variety of ways. Why would we want to “colorize” gold at all?
Design creativity of course, but the color purists (you know who you are) have their say too. After all there are two other precious metals that are white. I happen to like white gold on its own or for contrast. We can not just use platinum instead. A larger item can be unwieldy in platinum, and silver is a different look and market anyway.
For most jewelers white gold is also perplexing at the base alloy level. I notice via the phone calls I receive-many well trained casters/jewelers tinker in yellow alloy formulas, far fewer in “home made” white gold. Some manufacturers will mix their 24kt with alloys for yellow but order the white golds as karated casting grain. They understand white gold is even more difficult to properly blend with the master alloy. Bench jewelers all have tales of woe. Many from whenever white work went wrong. Casting shops small and epic in scale share the symptoms.
There are two common ways to make white and a few uncommon ways. In the United States we use nickel to whiten far more than any other way. Europe has restricted the use of nickel in a very severe manner. This due to the fact that some people are allergic or sensitive to nickel in contact with the skin. The common alternative is palladium. So palladium is the white gold most common in Europe and rarely found here in the USA . A rarely used relatively new way to whiten gold is with manganese. The problem there is extreme oxidation and manganese reactions that appear as a yellow tarnish.
Soldering is a challenge as well. One friendly California cynic I know saw our manganese white gold and said “now we’ll find out who is allergic to manganese”. Made me laugh and then I realized the implications of unleashing a poorly understood alloy on the trade in general. Only the marketplace can tell us for sure what works. Low karat golds like 9k for England can be made with silver as the whitener, but this failed to achieve good color in 14kt or higher. So, about three ways to go about this task in the USA .
Each common alternative has its own good and bad points. Lets begin by starting with nickel.
In general, a six percent or so Ni content in 14kt gold gets us reasonably fabricated white color that will require rhodium plating of durable quality. At 10% nickel we will expect better color at the consequence of reduced flexibility. Go much higher and forget all about pave setting, and thin sheet. 10kt and 18kt are different in the details like the percentages, but the basic facts stay. More nickel gets you better white color in any gold at the cost of higher temperatures for casting and a dramatically more brittle nature. Basically white gold with enough nickel to avoid rhodium plating is not very flexible at all. Other issues such as fire cracking (cracking while raising the temperature as in annealing) exist as well. On the positive side, all this is well understood by alloy makers, casters and well trained or experienced bench work professionals. Nickel white gold is very durable and often very heat treatable. Practically every American bench jeweler knows how to deal with the nickel issues. Very clever practitioners will exploit these properties to their competitors’ frustration.
Palladium is a platinum family metal that is the preferred option anytime nickel is not suitable. Two trade offs here, the first is that Pd white gold often casts at temperatures in excess of 2000f. that is above the temperature where many investments begin to cause porosity. Some casters use additives in the investment or even resort to investments based on feldspar like platinum casters often use. The other problems presented are in no small part financial. In volumes typical of our trade nickel costs perhaps seven dollars per pound. Palladium has been as high as $1000 per ounce and more. These days it runs around $250 per ounce or about $3,600 per pound! Quite a comparison. If you are a jeweler who reports expenses to the accountant be sure he or she sits down before you explain this cost. As karated casting grain palladium white alloy can easily add forty dollars per ounce in 14kt or 18kt white gold. A 14kt alloy containing 14% Pd will give you good color and a very nice soft metal that is a pleasure to roll, engrave or pave set. Rhodium plating might be optional depending on your customers preferences.
Last year we sold hundreds of thousands of ounces of white gold. Palladium alloys amounted to a few hundred ounces. Again quite a comparison.
White gold makes us choose between very white color and workability, temperatures or cost. When you must compromise color for working properties, use good durable rhodium plating. The crucial point is to choose the trade off carefully.
When you understand exactly how you will work the white gold, what temperatures your casting setup can handle, and how to durably rhodium plate when needed is how you can always have the right white gold. Now go on out there and make the right white gold work for you not against you.