Our series is aimed at newcomers with our lovely shared hobbies. This time, we will explore the world of accuracy of high-end mechanical wristwatches. So if you are considering buying your first “real” watch, this is all you need to know about precision timekeeping and certification.
Of course, our veteran readers are welcome to read and share their thoughts in the comments section below. Make this page useful to budding clock lovers together.
Why a gorgeous watch isn’t as accurate as you expected
“These watches cost 10,000 euros, but they’re not even more accurate than supermarket watches that average 10 euros!” Critics in the luxury industry love to impose this argument, and it’s convincing, isn’t it? We are all crazy and we are pulling fast industries at our expense.
Well, that’s not the case. Quartz and digital technology allow timekeeping with a much higher level of accuracy than mechanical timekeeping these days. Still, it’s like saying that manual espresso machines are outdated, as you can drink coffee 15 times faster with the pod. Some people simply prefer a more mindful and controllable process of hand dialing a morning cup of espresso. They’re probably willing to pay more for it too. A single metric with subjective relevance cannot reduce product value to performance.
The mechanical wrist watch is almost the same. Sacrificing accuracy for purely mechanical timekeeping experience. For example, one advantage is that it is essentially infinite maintainability, turning a reliable watch into a permanent one. This sacrifices physical limitations. In extreme cases, mechanical wristwatches can be accurately made in about 1 second per day. Most run within 4-20 seconds a day, depending on some aspects that will enter later. This has little practical meaning to you, but the wearer is less accurate than quartz or digital watches on a daily basis. This is a trade-off. In addition to the romantic appeal of mechanical movements, you can argue that it is more reliable. After all, you won’t be surprised by a dead battery that will render your watch useless.
A timegrapher for measuring the accuracy of a watch
Mechanical watches are short-lived
It’s good to understand that mechanical watches have dynamic accuracy. First of all, it is affected by environmental factors such as temperature. The direction of the watch also affects its accuracy as gravity draws balance from different angles.
Image: Tempus
Additionally, the mechanical watch movement is as accurate as its regulations. Chronometric performance can usually be adjusted in a variety of ways. This will be done by the watchmaker during the service. Over time, the accuracy of the watch will decrease due to wear, deterioration of lubricant, and the possibility of dirt buildup. Impacts, magnetic fields, or other external influences, such as different climates, can speed up the process.
In short, the movement of the clock is inherently inaccurate. It simply has the potential for accuracy, and it is achieved through regulation, proper use, care, service and many luck. Your watch runs at +3 seconds per day when newly refurbished, but -7 seconds per day after a year.
What determines the potential accuracy of a watch
Some technical aspects determine the accuracy of the watch. I was once considering using a modern version of the old Peseux 7001 Ultra-thin movement on my debut VPC watch. However, I wanted it to run within the COSC standard (-4/+6 seconds per day – more details later). This movement has a very small balance wheel, and its inertia proves to prohibit it from being regulated very accurately. I couldn’t do it reliably enough to consistently pass the required test. Does it make it less move? Now, only with this one potential accuracy metric.
In general, movements with higher beat rates can be more accurately regulated. This is because we are technically tracking time. So, is a higher beat rate better? Well, that depends. The downside is that it shortens the watch’s power reserve and increases wear. This is why the PowerMatic 80 Caliber on Swatch Group has a lower beat rate. It sacrifices the accuracy of the 80-hour power reserve and reduces wear on moving parts. It’s a matter of priorities.
Certify the accuracy of the watch
Precision timekeeping became extremely important as people began sailing around the world. The so-called “chronometers” were used for navigation. The more accurate the chronometer, the more you know exactly where you are going. Early marine chronometers were stored in impact boxes, and only the ship’s navigators were allowed to operate. Just imagine forgetting to wrap it around. You will soon be lost in the sea and be blamed for the voyage of heaven.
Hamilton Marine Chronometer – Image: Anthony Grey Watch
This need for accuracy has led to the emergence of the practice of chronometer authentication. Watchmakers also used independent certification bodies to fight each other with accuracy. Most famous is the official Swiss death chronomatoress, perhaps known as COSC. COSC tests each movement for 15 days at five positions and three temperatures. Average accuracy should be run from -4 to +6 seconds per day. Once the movement passes, it can be labeled as a chronometer.
Some manufacturers go even further and add more rigorous testing. This is why Rolex reads “transcendent chronometer” on the dial with daily accuracy of ±2 seconds. Metas is another test body with additional testing for more stringent performance certification. Simply put, Chronometer certification is an additional value and costs additional costs. So you will usually find it on a more expensive watch.
In summary
There you have it – the very basics of mechanical wristwatch accuracy and certification. Hopefully, as you know, accuracy is one of many specifications that need to be carefully balanced. That’s also a fleeting moment. Some watch brands decide to sacrifice accuracy for longer power reserves and reduced wear. Others prioritize accuracy over everything else and strive for the maximum possible accuracy of timekeeping.
Of course, the main function of a watch is to communicate time. If you can’t rely on it, what use is the watch? Therefore, accuracy is an important performance factor, but it is not the last word on watch quality. Some manufacturers prioritize that, but they aim to acquire external bodies to prove their chronometric performance, while others simply don’t. You need to realize that many non-chronolometer movements can be adjusted within the chronometer specification. This means there is no mechanical or essential difference between very accurate movements and so many reliable alternatives. In this sense, we should always talk about the possibility of motion accuracy. This is because it really changes with movement.
How important is accuracy? You are the only one who can decide what you need and what you need when it comes to chronometric performance.
If you have other insights on accuracy and certification that you think might help newcomers in our shared hobby, please share them in the comments below!
