Jewelry Metals and Allergies
Q: My wife seems to be allergic to every metal, so she has trouble wearing rings. What can we remake her wedding band from that won’t cause a reaction?
A: While there is no metal to which nobody ever has a reaction, some are a lot less likely to cause trouble than others.
Of the usual precious metal alloys, it’s most common for allergies to be not to the actual precious metal, ie gold, silver, platinum, but rather to the alloying metals, especially copper, or even more, the nickel in many white golds. It’s useful to note that if your wife’s ring is made from a white gold, then her reaction to it is not uncommon. A fairly significant percentage of people are quite sensitive to nickel-based white golds, which are commonly used in the U.S. (although they are banned in Europe) But in any case, purer alloys of gold, ie higher karats, may be better. In gold alloys, a 22K gold might well work, especially if it’s an alloy with little copper, but more silver, although this is softer than the alloys incorporating copper. Or, how about just pure 24K gold? It’s quite soft, too much so for many designs, but not all. Designs made to take into account the softness of pure gold can be quite durable. Simple heavy wedding bands in pure gold are wonderfully beautiful and long-wearing, and few people have any reaction to them.
Even more commonly associated with a freedom from allergic reactions, is platinum. In addition to platinum being even less chemically reactive than gold (which is already not very reactive), it’s usually used in an almost pure state (90 to 95 percent pure), and is often alloyed with other metals that are also in the platinum group, especially iridium, which is considered equally hypoallergenic. It’s common, for example, for surgical implants to be faced with platinum. Pacemakers, for example, are sometimes made with a platinum—covered exterior, for just this reason.
You also have options in less valuable materials that many people find to be hypoallergenic. Titanium and niobium are both highly reactive chemically, especially with oxygen. What this means is that they both bond extremely tightly with oxygen, and the resulting titanium or niobium oxides are very hard and stable, and the metals, in normal use, are always covered by an almost impervious surface film of these oxides. The oxide layers can be enhanced by heat or voltage to exhibit beautiful interference colors too. Both of these materials are also commonly used in surgical implants, because of the rarity of allergic reactions to these metals, and both are quite reasonably priced. Not all types of jewelry can be made from these, however, since neither one can be soldered in the normal manner. But modern equipment allows them to be welded and cast quite well, if you’ve got a jeweler sufficiently acquainted with the specific needs of these metals.
The classic hypoallergenic metal is still surgical stainless steel. Inexpensive and long—wearing, it can also be made into quite attractive jewelry. In recent years we’ve also seen some exotic materials used in wedding bands. I’m thinking of tungsten carbide in particular. A dark grey metallic material, more like a ceramic actually, with a hardness that usually suggests its most common use, as cutting tools. But that same hardness means that those few firms that can machine it into a wedding band have produced something that you’d have to work very hard to scratch or ding up. And I’ll bet that it’s pretty good in the allergy department too.
by Peter W. Rowe M.F.A., G.G.