COSC Introduces New „Excellence Chronometer“ Seal

In July last year, COSC CEO Andreas Wyss, in an interview with Swisswatches Magazine, had already hinted that the existing certification offering was to be expanded. There was talk of ‘Super COSC’.

“The aim is to improve the certification process and expand our range of services. This will enable us to better meet the changing requirements of the watch industry. I can’t give you any specific details yet,‘ said Wyss at the time.

’But it will involve testing watch heads, which will open up further testing possibilities in terms of water resistance, magnetic field resistance, power reserve and so on,‘ he continued. ’The overarching goal is to further expand COSC’s role in promoting Swiss watchmaking.”

Established standard: COSC Certified Chronometer

The COSC is now officially introducing this standard and offering two certification levels for the first time. The first is based on ISO standard 3159, which has been in use since 1976 and forms the basis for the well-known ‘Certified Chronometer’ seal of quality.

The standardised testing procedure includes static tests of the movements in five different positions and at three defined temperatures (8 °C, 23 °C, 38 °C). The movements are then checked again daily to ensure that they are performing flawlessly. The entire process takes between twelve and twenty days.

Only mechanical movements that meet the following accuracy criteria receive the coveted ‘COSC Certified Chronometer’ label:

• Average daily rate: -4/+6 seconds
• Maximum deviation: 5 seconds per day
• Average rate deviation: 2 seconds/day
• Maximum rate deviation: 10 seconds per day
• Gang difference in vertical and horizontal position: -6 to +8 seconds/day
• Temperature-dependent deviation: -/+ 0.6 seconds/day
• Resumption of movement: -/+ 5 seconds/day

„COSC Excellence Chronometer Certified“: Practical relevance through extended performance requirements

The second, new level is a further development of this existing standard and awards the ‘Excellence Chronometer Certified’ seal of approval. For this purpose, fully assembled watch heads are subjected to an extended test catalogue under realistic conditions. The additional performance requirements are also:

• (-2) (+4) s/day: A reduced tolerance of 6 seconds per day (compared to 10 seconds according to the ISO standard) is considered a criterion for the new certification.
• 200 Gauss: The magnetic field resistance test is performed at 200 Gauss.
• Power reserve: The specified power reserve is checked.

‘This new certification supports manufacturers in overcoming today’s challenges and underlines COSC’s ongoing commitment to excellence and innovation in Swiss watchmaking, without compromising the independence and rigour of its testing procedures,’ explains the Contrôle Officiel Suisse des Chronomètres, explaining the reasoning behind this step.

„COSC Excellence Chronometer Certified“ – Excellence comes at a price

The current certification fee for the ‘Certified Chronometer’ seal is ten Swiss francs per movement. The new ‘COSC Excellence Chronometer’ certification costs between 30 and 35 Swiss francs.

‘Excellence comes at a price, but it is definitely a competitive advantage. The new standard designation is “Excellence Chronometer” and can be displayed on the dial,’ explains the COSC. The implementation is planned for October 2026.

Reorientation: From certification organisation to brand

The new seal of approval is part of COSC’s strategy to strengthen its brand positioning among end customers. Among other things, this includes certification cards that give buyers access to the test data for their watches.

The new website also explains the details of chronometer certification in a way that is easy to understand, even for watch novices. Industry experts will still find more in-depth information. In addition, there are extensive activities on the social media channels of the COSC and its more than 60 partner brands, which are also aimed at attracting newcomers to the world of watches and raising awareness of the value of precision Swiss watchmaking.

‘By certifying precision, embodying excellence and promoting this, we are contributing to the global reputation of the Swiss watch industry,’ explains Andreas Wyss.

About COSC

Certifications play an important role in the watch industry. Some confirm authenticity, while others assess the quality of a watch or its movement. One of the best-known and most renowned institutions in this field is the Contrôle Officiel Suisse des Chronomètres (COSC) in La Chaux-de-Fonds, founded in 1973.

The Swiss testing centre for chronometers, i.e. high-precision watches, is not a public institution, but a non-profit organisation recognised as a voluntary self-regulatory body for Swiss watch and movement manufacturers.

In three independent laboratories, 160 employees test exclusively Swiss-made movements and watch heads – both mechanical and quartz. According to the COSC, around 40 per cent of all Swiss mechanical watches exported are currently certified by them.

Since its foundation, the COSC has carried out almost 55 million certifications and awarded the ‘Certified Chronometer’ label. Now the ‘Excellence Chronometer Certified’ award has been added.

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