The Contrôle Officiel Suisse des Chronomètres (COSC) is an official Swiss organization responsible for certifying the accuracy and precision of mechanical watches. Established in 1973, it conducts rigorous testing on timepieces to ensure they meet high standards of performance. Watches that pass the COSC tests receive a certification known as the Chronometer designation. This certification guarantees that the watch has undergone extensive evaluation under various conditions, confirming its reliability and precision in timekeeping. The COSC plays a crucial role in maintaining the reputation of Swiss watchmaking excellence.