Switch and miss
I have a word of caution when it comes to white gold alloys—choose your preferred mix carefully and stay with it if possible and here’s why. Thirty years ago, we made our own 18-karat white gold from a proprietary base metal mixture that we combined with pure gold in the shop. It was a dream metal to work with—its ductility and ability to be re-used several times while retaining its working properties were amazing. While it had a pretty good white colour when freshly polished, after a relatively short period, it acquired surface oxidation, leaving it a rather unattractive brownish tone. When used in combination with yellow gold for a two-tone piece, there was almost no difference between the yellow and white colour, even when the surfaces were matte finish. We could have rhodium-plated this, but it didn’t look very good and required periodical re-plating.
Twenty years ago, I switched exclusively to using a 19-karat white gold alloy. I buy this already mixed as casting grain from a Canadian supplier. It has its pros and cons. The colour is as close to platinum white as I have found. It neither changes colour with time nor does it require rhodium plating to look good. It provides excellent contrast when used in combination with yellow and rose gold. It also recasts well, provided some new material is added. Now for the cons—it contains nickel. It is also quite hard and requires some care in casting and annealing for fabrication. That said, it responds well to both soldering and especially laser welding.
Being limited to one white gold alloy is problematic, as there is always the risk the supplier will change the blend or stop making it altogether. Therefore, over the years, I have experimented with white gold alloys from a variety of suppliers to see if there is a better alternative to my current standard 19-karat. Some were excellent products, but there was one major roadblock to switching from the metal we were using: consistency. I used one of the alternate 19-karat white gold alloys to make an engagement ring for a client. The metal cast, worked, and polished beautifully and had a nice white colour, albeit not exactly the same as our standard alloy. There were no compelling benefits to switching, however, and I decided to stick with the existing alloy going forward. This decision proved to be a good one because two years later, the client returned to have a matching wedding band made. I had not recorded the fact we had used the new alloy for the original ring, and we made the new band in our usual blend only to realize the two rings simply did not match. We had to buy gold from the other supplier and remake the band. Not a good financial situation!