Watch Case Materials – Precious Metals
Like all technical features of watches, the choice of case material has changed over time. Some materials that were once popular have become uncommon. Some have gained popularity over time. And some were and are popular. In this article, I’ll focus on various precious metals.
Silver has been the most common case material, ever since watches were around. From the 17th century up to the 1930s, there’s hardly any metal that has been used as much as silver.
0.925 – Sterling silver
0.925 silver, meaning 92.5% of pure silver in the alloy. It’s the most common alloy in English cases, but not the only one. Silver is a light and soft metal, so it’s not the best material out there. Still, as far as value goes, it’s the silver alloy to go with.
80% pure silver was the alloy of choice for pocket watch cases made either in Germany or for the German market. The 0.800 purity stamp is often accompanied by the German silver hallmark, the crescent moon with a crown. Value-wise, it’s not the best choice. In terms of durability, it should be better than sterling silver. Still, that depends on what the remaining 20% of the alloy is made of.
The fall from grace
Silver was primarily gone from watch cases by the 1940s. Customers weren’t interested in a material that was costly, way less durable than stainless steel, and wasn’t gold. Of course, silver still made an excellent dial material. As far as cases go, you could still see it around in the 1980s, in the low end of Cartier watches, as a base metal in gold plated cases.
The various types of gold
Like silver, gold was around as case material since the beginning. Of course, it isn’t an efficient case material. Just as it’s with silver, the value of the alloy is inversely proportional to its durability.
0.375, or 9-karat gold
Like sterling silver, 9k gold was mostly a British market thing. It’s the most durable gold alloy. There’s also 8k (33.3%) gold, which, although it’s relatively common in jewelry, I’ve never seen it used as watch case material. So, 0.375 is least likely to get banged up quickly, but for obvious reasons, it’s also the cheapest.
No less, it made perfect sense in watches. Nowadays, we treat a vintage watch like an egg, fully aware of its fragility. But back in the day, the middle-class working man who’d buy a 9k gold watch wouldn’t have babied it nearly as much as we collectors do. It would’ve been placed on the dresser or the nightstand, bang against cufflinks, and so on.
And that’s not to mention that it would’ve likely been someone’s only watch. For a collector with a compulsion to hoard, like yours truly, this is relatively hard to fathom. But, well, that’s the way it was.
While 9k is more popular in jewelry than in watches these days, watches with 9k cases are still being made. Not by any big-time brands, though. I know that Rotary still uses it, but it’s hard to say what’s less popular now, 9k cases or Rotary itself.
I don’t think I’ve ever seen a 10k gold case in a watch not made for the American market, and outside a locally made American case. And even then, it never was common as a case material on its own. Far more common as the gold layer in rolled-gold plate and gold-filled cases. Similarly, now and then you’ll see the even more uncommon 12k gold used as plating, and rarely as the single material in a watch case.
0.585, or 14 karat gold, is widely considered to be the perfect compromise between value and durability. In jewelry, it’s the alloy of choice for engagement and wedding rings. In other words, the items that are meant to be worn daily, and which will be exposed to wear and tear.
14k gold scratches easily. If the case back protrudes beyond the level of the tips of the lugs, you’re better off placing your watch on a soft cloth or even paper. Otherwise, you’re up for more than a few scratches on it.
Along with 18k gold, ever since the 19th century, it’s the most common alloy used for gold cases.
0.750 – 18 karat gold – is the peak of what you can safely use for a watch case. Nowadays, brands from the mid-luxury tier (like Longines) and up don’t use any alloy of a lower or higher fineness. Of course, occasionally, you’ll see the oddball 22k case, but that’s likely a smaller manufacturer just trying to be different.
Still, gold of any purity higher than 18k is better off as a pen nib or a pendant. Besides, any watch with a case made of 22k gold likely has its value in craftsmanship rather than in the amount of gold.
So, why even bother to make a watch case in 22k gold? Except for perhaps marketing to those who favor strength in numbers, there’s no point in that. Especially that this “strength in numbers” means weakness in the structure, as far as gold goes.
Yellow, Rose, or White?
Now that we’ve got the purities sorted out, let’s move on to another point – the color. There’s very little that you can do about the color of 24k gold. However, in any gold alloy with a notable percentage of other metals, it’s what these “other metals” are that defines the final tone or color of the gold.
Red/pink/rose gold will always have a high content of copper. Rose gold has been growing in popularity since the 1990s, and manufacturers use it more often than yellow gold. A matter of fashion. The biggest downside of rose gold is its tendency to discolor. While gold on its own is not very reactive, other metals in the alloy are. Copper certainly is. In something as exposed to many environmental factors as a watch case, using too many other relatively reactive metals in the alloy leads to the alloy losing its red tone and yellowing over time.
Watch manufacturers like Rolex and Omega have worked on their proprietary rose gold alloys (Everose and Sedna, respectively), which are meant for a case to retain its color for as long as possible.
Of course, you can see vintage watches with their rose gold cases still in good shape in terms of color. The question is how extensively such a case is worn.
Now, this is usually not white gold, as it’s plated. The base of “white gold” is pure gold mixed with white/silvery metals, like silver, nickel, sometimes also palladium. Well, if palladium is used, it’d better not be the only alloy. Otherwise, you’d be better off with a platinum case. But more on that later.
So-called “grey gold” takes a substantial amount of palladium to obtain, so cases using grey gold are more expensive than standard white gold, and even more than yellow or rose gold.
So, you can make gold of a pale yellowish color. It still isn’t white gold. So, what’s done to achieve that beautiful, pale silver-tone and glint? The whole thing is plated with rhodium. Rhodium, apart from giving white gold its final color, also protects the surface from developing oxidation.
Is white (not grey) gold durable? No, not really. In the end, after years (maybe decades), that yellow-ish tone of the base alloy will start to show, as the rhodium plating gradually wears off.
Yellow gold is the most common thing in jewelry, and still popular in watches. Yes, these alloys are prone to develop oxidation, but that’s easy to clean off. They’re very stable alloys, with hardly any tendency to change color over time. Therefore, it’s the most practical choice.
Note that, like with various tones of rose gold, there are different kinds of yellow gold. Some alloys have a warm yellow tone. Some will have a paler, colder hue. Some even have a very odd appearance with a trace of green in their glint.
Most upper tier luxury and high-end brands have, at some point, made a watch in platinum, or have at least one in the catalog. It’s the most valuable case material in regular production watches. Well, with the price of platinum standing at 899 USD per ounce as of December 1, 2019, that’s no surprise. And platinum is heavy. Heavier than gold. So, it’s no wonder that platinum-cased watches cost tens of thousands of dollars.
It’s also way more practical than gold – it’s more robust and unreactive. Note that platinum used in jewelry and watch cases is also an alloy. Nearly always 0.950, which means that the platinum content is 95%
Vintage watches in platinum are rare. Even the brands of the Big Three – Patek Philippe, Audemars Piguet, and Vacheron Constantin used it rarely until the 1980s and 1990s.
Jewelry companies like Tiffany & Co., which apart from importing complete watches have also imported Swiss movements to the US and cased them on their own, now and then cased some in platinum. And even then, presumably, some of these were custom orders. It made very little sense to offer regular production models in this metal.
I’ve only seen it used as case material once. That was in the Vacheron Constantin Quai de l’Ile, more than a few years ago. I reckon it doesn’t get any rarer than that when it comes to precious metal cases. It’s way more challenging to work than gold or silver. Reasonably durable, not very reactive. However, it does change color in higher temperatures occurring during the manufacturing process and is more likely to do that than any other metal used for watch cases.
So, do you think that platinum is expensive? Palladium is there to prove you wrong. There’s a reason why it’s not as widely used as a standalone material as it’s in alloys. Sure, it’s used as an ingredient of white gold. And it’s used for items like pen nibs, now and then.
As mentioned before, as of December 1, 2019, platinum stood at 899 USD per ounce. At the very same moment, palladium averaged at 1,853 USD per ounce. That’s more than twice the average for platinum. No wonder that no one wants to use it for making watch cases. It’s expensive and tricky to work with. So, why bother.
All in all
Precious metal cases are lovely to look at, and even a watch with a silver or 9ct gold case is a cool thing to own.
Still, when it comes to practicality, they’re not better. They’re easier to scratch and often develop a residue over time.
In the next part, we’ll have a look at different kinds of materials that meet different standards.