At the 2025 Geneva Watch Days, the COSC rolled out a large-scale activation. Within the Pavilion’s Culture Club, the label engaged not only with watch industry professionals but also with the general public by hosting a four-day regulation contest. A true “Top Chef” of watchmaking.

40 Sellita movements, 40 contenders, and just one hour to reach ultimate precision, measured acoustically, with the tick-tock as our most instinctive perception of time. From there, the journey led to the COSC laboratories, where the movements faced the ultimate chronometric trial: 5 positions, 3 temperatures, and precision captured through optical cameras. The very same process every certified timepiece must endure: an odyssey of accuracy at the very heart of Swiss watchmaking.

CEOs, media, influencers, collectors as well as watchmakers, all stepped up to the challenge. What began playfully soon took on the intensity of an Olympic contest, as each tried to master the quest for precision. Luckily, the students of the Geneva School of Watchmaking were there to guide them, unveiling the subtle art of regulation, where patience, dexterity, and a steady hand make all the difference.

1. Yannick Nardin, Journalist, Editor-in-Chief, WorldTempus

2. Amandine Perret-du-Crêt, Influencer, @watch_it_with_amandine

3. Patrick Pruniaux, Co-Founder, Chairman & CEO, Sowind Group (Ulysse Nardin & Girard-Perregaux)

4. Maxime Chavanne, Watchmaker, Bulgari

5. Florent Perrichon, CEO, Laurent Ferrier

6. Andrea Casalegno, Influencer, @iamcasa

7. Samuel Nicod, Watchmaker, Ulysse Nardin

8. Ernesto Quant, Collector

9. Emmanuel Schneider, Content Director, FHH

10. Clément Meynier, CEO, Depancel & Amida

This edition of the COSC calibership challenge ends with a unanimous conclusion: precision, the true grail of watchmaking, is acquired with patience and discipline. The results obtained confirm the added value of the “Chronometer” label: the difference between the instantaneous rate observed and the average daily rate measured in the laboratory perfectly illustrates the relevance and reliability of the COSC protocol. The saga of these 40 movements also opened the doors of the certification laboratories to the public. Through social media, viewers discovered the meticulous testing process, the professionalism of the operators, and the exemplary neutrality symbolized by the “Certified Chronometer” seal. On the 40 timepieces submitted, 32 achieved the certification, a remarkable success which proves that the COSC tolerance range (-4 / +6 seconds) is both demanding and attainable.