COSC is just a cynical marketing exercise

CSOC stands for Contrôle officiel suisse des Chronomètres and it sounds fancy but for the masses. The company is not part of the Swiss government or any international standards organisation. It is another Swiss company that claims to override other Swiss manufacturers claims related to a watch’s  accuracy at keeping time. 

The term COSC is often used by the less experienced and ‘self claimed watch experts’, repeaters of the top search results on Google, those running online stores for new and used watches needing a catchy point of marketing and selling point or those who work of those watch companies. So why is COSC a marketing exercise and a bit of a scam?

The CSOC claims to be a non-profit company with ownership by the major Swiss brands, that apparently measures and then certifies the accuracy of a watch with mechanical or quartz movements and gives them a stamp of approval or certificate. They only test ‘Swiss made’ brands hence not an international organisation. That said their ultimate ownership is as vague as how they actually do their testing. There is no mention of equipment that they identify how they can actually measure them and they certainly can’t measure every watch that is made. What is also certain is that only the movement is ‘certified’ not the actual completed watch just the mechanism inside them. Their latest annual report said that they certified 2428849 movements in 2022. 

You can buy your own watch timing measurement machine commonly called a Timgrapher quite easily and do your own watch accuracy certification result that is as competitive or arguably better than one with a COSC certified movement. In fact I may just set up my own non-profit company to do just that.

So what does COSC certification actually mean? It means a Swiss watch’s movement meets the expected time keeping standard you’d expect in any watch movement on 2025 but only at a certain point in time and in an implied controlled environment. (Note its a test of the movement not the actual watch) It’s not a challenging standard in 2025 (just search for ISO3159) as complete digital watches easily beat it and it certainly not even close to Atomic time keeping. The fact the ISO3159 is contingent on a non existent organisation possibly replaced by COSC implies this is just a another Swiss barrier and devalues the ISO brand. More on that later. 

After researching, as much as I can about COSC watch certification, the more I am more convinced that COSC it is an expensive marketing exercise. The reasons are clear to me and now to you!

50 years ago when technology and manufacturing and industry knowledge was not quite as advanced COSC would have meant something to ‘Swiss made’ watches but in 2025 it does not have the same importance – blame the Quartz, smartphones and the internet. 

It devalues the watch brand that is using the COSC branding. Especially the more storied brands like Rolex, Omega, AP and even Longines that have a much longer history than COSC. After all these brands would not have survived if they hadn’t been reasonably accurate in the first place. It is like telling the world that your quality control is not very good so relies on another company (it also has interest in) to validate their quality. That said cheaper or newer Swiss brands which appeal to a different set of buyers may need a stronger spec point. 

Most wrist watches in 2025 don’t sell based on how accurate they are. They sell mostly based on any number of factors including brand, hype, design and history. For example the ‘Moonswatch’.  That said there is no sure fire way to create demand for a particular watch as Gen Z in particular don’t think the same way for Gen X buyer would. 

Due to the double standard of testing quartz vs mechanical the standard clearly shows that Quartz are tougher more accurate and ultimately more reliable. If the same tests where subjected to a mechanical watch it would certainly fail.  That said there are grades of Quartz accuracy too but that’s another story. 

Once the mechanism leaves the testing grounds or inserted into a watch then into the real world and actually worn on your wrist I don’t think you can whole heartly claim the same accuracy. Just too many variables! 

COSC certificate apparently means you can describe or market your watch as a Chronometer but only if you are a Swiss brand. Yes folks COSC is marketing.  Note that a Quartz watch is more accurate and consistent in any circumstance is rarely Chronometer so marketing a mechanical watch is COSC is a bit like a circular reference in Excel…

Conclusion: COSC certification is of dubious value. So when someone mentions COSC as a selling point please roll your eyes and click away.