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The term “chronometer” dates back more than 150 years, and originally referred to marine clocks whose accuracy enabled precise navigation. In the 20th century, it became a designation of timekeeping excellence reserved for only the most accurate watches. A byword for reliability, chronometer certification is fundamental to the reputation of brands including Rolex and Omega, but has seen its value decline with their adoption of more demanding in-house standards.
For more than half a century, Swiss watches have been certified by COSC, a not-for-profit organisation established in 1973. Its independent testing regime stipulates a level of daily variation in timekeeping that, if met, permits the watch to be sold as “chronometer certified”. Based on an ISO standard first drawn up in 1976, its headline criteria — that a watch should lose no more than four seconds and gain no more than six in a 24-hour period — have been improved upon by several brands in the past 20 years.
Now, after decades of near-silence, COSC has announced it will introduce a more stringent standard of accuracy. The so-called “Super-COSC” will make its debut in September 2026, and build on rather than replace its current level of certification.
“The market is changing,” says COSC’s CEO Andreas Wyss. “Rolex has its superlative chronometer certificate; Omega its master chronometer. We knew that the ISO certification that we use today is old, maybe too old, but it’s difficult to change that. So we took control and said we have to do something first.”
Full details of the upcoming standard are yet to be announced, but Wyss said it would almost certainly improve the standard for daily accuracy by cutting the threshold in half, as well as testing other attributes such as magnetic resistance and power reserve, to provide a more rounded certification of quality. The Super-COSC would also test cased-up watches, as opposed to movements — which is the norm for current COSC testing — to better represent a watch’s performance in the real world.
Wyss says the improved standard, as well as COSC’s decision to be more vocal in promoting its role in the industry, reflects a need for the organisation to improve its image.
“We questioned our customers to know the perception that they have of COSC and the value of the certification. Most of them said the image of COSC is dusty. They said the ISO certification is good, but it’s not sufficient. The end customer needs more.”
Exactly which brands submit watches to COSC, and in what quantities, has been a secret since 2016, when the organisation ceased to disclose the information in its annual reports. Rolex, which Morgan Stanley estimated sold 1.18mn watches in 2024, submits every movement it produces to COSC, as does Breitling, which sold an estimated 160,000 watches last year.
Omega’s Metas-certified watches must first achieve a regular COSC certificate; between them, these three constitute the majority of COSC’s custom. In its annual report for 2024 COSC says it issued 2.38mn certificates, a decline of 5 per cent on 2023.
“Breitling was among the brands encouraging COSC to update its certification standards,” says the company’s chief operating officer Daniel Braillard. “We submit 100 per cent of our production to COSC testing — both mechanical and quartz — which provides customers with the reassurance of proven precision, reliability and quality. Advances in technology and materials allow us to improve the performance of our watches, and it is therefore necessary and important that testing criteria evolve as well.
“The current standards remain highly relevant, but they no longer fully reflect the capabilities of modern watchmaking. This is why the Super-COSC initiative is so compelling: the new criteria will apply not only to the movement but to the entire watch, with stricter tolerances for precision and added new tests for resistance-to-magnetism testing and power reserve.”
Braillard says Breitling is considering whether to submit watches for Super-COSC certification in 2026. As the largest maker of chronometers not to have adopted any additional benchmarks, its support would be valuable to establishing credibility for the new standard.
For Wyss, the introduction of a new standard is not about competing with other tests. “Our goal is really not to enter in competition with Metas. Our message to the end customer is to say the watch you buy will function every day with no problem. We don’t say you can go on the Moon or in the Marianas Trench.”
For COSC, the move will have financial as well as reputational implications. Charging brands for certification is its only revenue stream. Wyss says it costs just under SFr10 per movement for standard COSC certification, and although no prices have been set for Super-COSC, it will cost more, as watches will still have to pass the existing test.
Wyss estimates that the upstream cost to a brand submitting a mechanical movement for COSC certification is around SFr50, which may also increase.
“All revenue generated from testing is fully reinvested into our operations and the ongoing development of our services,” says Wyss.