COSC (Contrôle Officiel Suisse des Chronomètres)

COSC, or Contrôle Officiel Suisse des Chronomètres, is the Swiss organization responsible for certifying high-precision watches called chronometers. To earn this certification, a watch must undergo rigorous testing over several days, demonstrating exceptional accuracy and stability under various conditions like temperature changes and positions. Only watches that meet strict standards are awarded the COSC label, ensuring they are reliable and precise. This certification is a mark of quality and craftsmanship, signifying that the watch has passed one of the most respected tests for timekeeping accuracy in the watchmaking industry.