COSC introduces new certification: Excellence Chronometer Certified
To mark the 50th anniversary of the ISO 3159 standard, the Contrôle Officiel Suisse des Chronomètres (COSC) has introduced a new certification.
It was developed by the COSC to meet today's technical requirements and the changing expectations of manufacturers and customers, and builds on the existing standard.
The new "Excellence Chronometer Certified" award is an extension of the existing "Certified Chronometer" certification.„ designed with additional or extended performance requirements:
- Finished watch: The tests were conducted at the Fully assembled clock conducted under realistic wearing conditions.
- (-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 stated power reserve is checked.
COSC with two certification levels
The COSC now offers two certification levels. The first, based on the ISO 3159 standard and used since 1976, forms the basis for the precision of Swiss watches: it awards the "Certified Chronometer" seal of approval.
The second stage, a further development of the existing standard, awards the "Excellence Chronometer Certified" seal of approval and tests finished watches under practical conditions.

„This new certification supports manufacturers in meeting today’s challenges and underlines the COSC’s continuous commitment to excellence and innovation in Swiss watchmaking, without compromising the independence and rigor of its testing procedures,“ explains the Contrôle Officiel Suisse des Chronomètres.
About the COSC
Certifications play a significant role in the watch industry. While some confirm the authenticity of a watch, others attest to the quality of a watch or its movement.
Some certify authenticity, others assess the quality of a watch or its movement. Among the best-known and most prestigious institutions in this field is the Contrôle Officiel Suisse des Chronomètres (COSC), founded in 1973 in La Chaux-de-Fonds. This Swiss testing institute for chronometers, i.e., for high-precision watches, is not a public institution, but rather a non-profit organization for voluntary self-regulation by Swiss watch and movement manufacturers.
The accuracy of Swiss-made watch movements – both mechanical and quartz – is tested; these movements are later used in watches of Swiss origin.
Since its founding, the COSC has conducted almost 55 million certifications and awarded the "Certified Chronometer" label. Now comes the award as „"Excellence Chronometer Certified" added.






