At the end of just about every watch story published anywhere (and long before there was a watch internet) there is generally a short block of text that lists the basic – and sometimes, not-so-basic – physical characteristics of a watch. Sometimes it’s obvious why they’re there – things like case dimensions, water resistance, and a general idea of where the movement came from are useful in getting an approximate idea of everything from whether or not a watch will fit on your wrist, to how much of an investment in actual watchmaking a given manufacturer has made.
Sometimes, however, it’s less clear why certain specifications are included. Jewel count, for instance. Many watch enthusiasts probably have some idea why watch movements have jewels in them, but some don’t. And yet the jewel count is not only a feature of spec sheets in watch articles, it’s also often specified by the manufacturer on the movement itself. Frequency is another one – most modern movements made in any quantity run at 28,800 vph, so why bring it up in the specs if that particular frequency is more or less ubiquitous?
But behind the numbers in the spec sheet is more than you might expect. Both taken all together, and taken individually, why they’re there and what they are is a window into watchmaking history, as well as into what makes any watch what it is.
Jewels in a watch are there for a reason – they act as bearings for the gear train. All the train wheels (that’s watch-speak for gears) have hardened, polished steel pivots and those pivots sit in bearings made of synthetic ruby, with holes drilled in them into which the pivots fit. The idea is to get energy from the mainspring to the balance with as little loss to friction as possible, and a steel pivot in a jeweled bearing, properly lubricated, is almost frictionless.
Jeweling was invented right at the beginning of the 18th century. It had immediate and obvious advantages but it wasn’t until making synthetic rubies became practical, that they became ubiquitous. They’re difficult to make – the stones are very hard and they have to be formed to very precise shapes to keep oil from running out of the bearing by capillary action. Today most jewels are friction-fit into the watch movement, although there are still some holdouts like Lange & Sohne that use chatons (jewels in brass settings that are screwed into place).
Just how much jewel count was associated with quality in the minds of watch consumers can be seen in the competition among some watch brands, in the 1960s especially, to produce absurdly high jewel counts by stuffing as many non-functional jewels into the movement as possible. Probably the height of this silliness was the Waltham 100 jewel automatic, which had 17 functional jewels in the gear train, with the rest attached to the outer edge of the mainplate, around its circumference. Finally, in 1974, the International Standards Organization created a standard for functional watch jewels (ISO 1112) and that, plus, probably, the quartz crisis, brought the whole thing to a screeching halt.
Nowadays, you don’t see low jewel counts, thanks to the economies of scale associated with producing them in such huge numbers for the watch industry. Even the humble Seiko 7S36, ticking away in millions of Seiko 5s, runs in 23 jewels. But a high count, especially in complicated perfect replica watches, can still mean more attention to improved functionality. The Omega caliber 321 has 17 jewels – fifteen in the going train plus two for the chronograph works. The Vacheron caliber 1142, which is the same base caliber as the 321, has a 21 jewel count, thanks to the addition of two more jewels in the chrono works and, I suspect (I’ve never seen a cal. 1142 stripped to the mainplate) jeweling for the center wheel, as well.
Oh, and want to know a really big reason jewel counts are on every movement – down to the lowliest zero (0) jeweled quartz movement? To import a watch into the USA the movement is actually required to have a jewel count stamped on it – and there are different import duties depending on the number of jewels, too (this means functional jewels, not decorative ones).
Water resistance, as it turns out, tells you less than you might think, practically speaking. There are two different standards for water resistance – for diver’s watches, and for water resistant replica watches in general. The main differences between the two are the rigor and frequency of testing – for a deep dive into what each standard means, check out our story on the similarities and differences from 2017.
In a nutshell, what the standards both shoot for is for the depth ratings to mean what they say they mean. So, for instance, a modern watch with a 30 meter water-resistance rating should be capable of staying dry if immersed in 30 meters of water. For reference, recreational diving takes place at between 30 to 40 meters. Now that doesn’t mean you should dive with a 30 meter water-resistant watch but it does mean that a modern watch, with modern gaskets and seals, should be perfectly fine for pretty much anything but regular swimming or regular diving.
For dive fake watches, the testing criteria are more rigorous, as they should be. The dive watch standard specifies 100 meter water-resistance as the minimum, which is already double the depth of recreational scuba so any modern watch with that rating should be fine for swimming, snorkeling, and of course, actual diving.
Most water-resistance ratings for dive replica watches tend to take us into the realm of the imaginary – 300 meters, for instance, is a thousand feet of water, at which point you’re talking mixed-gas technical diving, well beyond the requirements of even the most avid recreational or sport diver. There’s a certain amount of theater to modern depth ratings, but there’s also no doubt that most of us, damn the real world, just find a 200-meter rating more reassuring than a 100-meter rating.
This one is pretty straightforward – before you buy a watch you usually want to have some sense of how big it is (or isn’t). Thickness, case diameter, lug-to-lug dimensions, can all give you some sense of whether or not a watch is going to fit your wrist, and maybe more importantly, your tastes.
There is however an awful lot that even the most complete set of case dimensions don’t tell you. This isn’t to say that they’re useless but I’ve always felt that you don’t get much more than a first approximation of how the watch is actually going to feel on your wrist. One of the factors that affects feel significantly, for instance, is the ratio of height to width – a relatively small diameter case that’s also relatively thick is going to have a higher center of gravity, which means it’s going to tug a bit more on your wrist than you might think from the numbers alone.
Another intangible is how well a particular size works for a particular watch. As an example, we recently looked at the Arnold & Son Globetrotter – this is a 45mm watch and the domed crystal brings the overall thickness up to an implausible-sounding 17.23mm. Those are not encouraging numbers in terms of wearability, taken on their own. However, if you take them in the context of the watch as a whole – it’s a world timer with, as its centerpiece, a rotating representation of the Northern Hemisphere as seen from the North Pole – you start to understand why you might want an IMAX-size screen for this particular horological show. On the other hand, blowing up something like a Roger Smith or Dufour Simplicity to that size (or a perfect UK sale fake Rolex OP, for that matter) would not be such a hot idea. A 45mm version of those replica watches would look cartoonish, and not in a good way.
Beyond The Jewels: Frequency, Dimensions, Power Reserve
Frequency is one of those numbers you might wonder at anyone including at all – most modern automatic movements beat at 28,800 vph, so why include it if it’s almost universal?
It’s exactly because it’s almost universal that the exceptions are notable, and that it’s worth seeing in the watch specs. Every mechanical movement represents dozens of engineering decisions and each one of those is necessarily a compromise. A high beat movement – all other things being equal – will come with better rate stability. But all other things are never equal and seeing how the problems and benefits of various beat rates are addressed in the movement as a whole, is part of what makes movement design an ongoing and interesting problem. If a modern watch is running at 18,000 vph, that’s something that should catch your eye immediately. Ditto with frequencies above 28,800 vph – although makers of high frequency replica watches generally make sure their potential clients know they’re in the high frequency game.
Dimensions are interesting because they can help you have a more informed take on the rest of the watch. Let’s say you’re wondering what the big deal is about the movement in a Jumbo Royal Oak. Check the specs, and you’ll find out – the movement’s only 3.05mm thick and the no-date version is only 2.45mm thick. This is extraordinary since in one form or another this movement has been around since 1967 and it still holds the record for world’s thinnest full-rotor automatic movement.
Conversely, let’s say you’re looking at a steel sports chronograph with an automatic movement – an ETA 7750. That movement was not designed with slimness in mind and it shows – the 7750 is 7.90mm thick, and knowing that will help your expectations drive in the reality lane when it comes to the size of the case. The Royal Oak Jumbo overall is 8.1mm thick, for comparison – and that’s the entire watch, of course. A more modern chronograph movement, the AAA high-quality replica Rolex 4130, which powers the best UK sale replica Rolex Daytona, is much thinner, at 6.5mm.
And power reserve? Well, first of all it’s a fundamental property of a movement, along with frequency and jewel count – you can think of it in the same vein as horsepower figures in car reviews. Except for the most extreme cases they don’t tell you a whole heck of a lot about the actual overall experience of sitting in the car and driving it, but they’re an essential contributor to that experience. And it gives you a sense of what to expect from the watch in daily life – a watch with a 72-hour power reserve, for instance, will still be running if you put it down on Friday night and back on Monday morning.
One very important thing all these movement specs can do is let you know just what the actual origin of a movement is likely to be. Suppose a brand says that its chronograph movement is “a unique execution specifically to the requirements of our Maison.” Before you decide to applaud their hustle, you look at the movement specs and it’s 30mm x 7.9mm – well that alone ought to tip you off that just maybe the beloved Maison is indulging in blowing a little smoke. If you then go on to read that it’s got a 48-hour power reserve and runs at 28,800 vph, in 25 jewels, well … QED.
A lot of the time you can confirm any suspicions you might have by comparing the gear train layout, regulating system, and position of the jewels in the alleged “exclusive” movement, to what you think might be the base caliber. Train layout and consequently, jewel positioning are difficult to change.
It’s easy to skip the specs and it’s understandable that the technical side of watchmaking isn’t particularly interesting to a lot of owners, enthusiasts, and even, to some extent, watch writers. But understanding what they mean and why they’re mentioned can mean having a whole heck of a lot more fun – and it can also help you better understand exactly what goes into a watch, above and beyond what’s on a brand website or in a sales brochure (I may be dating myself with the last. Does anyone even print sales brochures any more?)