TEST
Invisible, yet measurable. Smartphones, earbuds, bag clasps… At Geneva Watch Days, the COSC gave a live demonstration showing how the magnetic fields found in everyday life can disrupt the rate of a mechanical watch. A particularly vivid way to introduce one of the criteria for COSC Excellence Chronometer: resistance to a 200-gauss magnetic field.
Because a watch doesn’t live in a laboratory.
MEASURE
And how is your watch doing? Visitors were invited to bring their own timepiece to have its rate measured free of charge. In just a few moments, everyone could discover its real-world performance and put a number on its precision. A simple, concrete reminder that behind every COSC certification, there is, first and foremost, a measurement.
To each their own watch. To each watch its own truth.
REGULATE
21 participants in the Calibership Challenge at Geneva Watch Days. One shared goal: to get as close as possible to 0 seconds per day (s/d).
For this new edition, participants with no technical watchmaking experience took on the challenge of regulating a mechanical calibre, guided by apprentices from the Geneva School of Watchmaking, who became instructors for the occasion.
But a single point-in-time measurement isn’t enough to decide between competitors. The calibers will now move on to COSC’s laboratories, where the acoustic measurement taken during the Challenge will be checked against optical measurement, in different positions and at different temperatures, over 15 days. It is only at the end of this series of tests that precision will have the final say and the 2026 Champion will be named.
The hand adjusts. The COSC decides.
PASSED DOWN
CHF 13,000 for the next generation. At the Geneva Watch Days charity auction, the COSC put up for bid a one-of-a-kind sculpture made from the winning calibre of the 2025 Calibership Challenge. Sold for CHF 13,000, it will help support students at the Geneva School of Watchmaking facing financial hardship.
Precision is measured. Excellence is passed down.
EXCEL
Test, measure, regulate, pass down. Precision is a starting point. Not a finish line. With the COSC Excellence Chronometer, the COSC intends to go further by evaluating the performance of the watch as a whole: a tightened precision range of –2 to +4 seconds per day (s/d), resistance to a 200-gauss magnetic field, behavior under conditions close to real-world wear, and compliance with the stated power reserve. A comprehensive approach to watchmaking performance, made tangible at the Geneva Watch Days.
A new milestone for the COSC. A new benchmark for Swiss watchmaking.
