The COSC Certification, or Contrôle Officiel Suisse des Chronomètres, is a prestigious designation awarded to Swiss-made watches that meet the highest standards of precision and accuracy. This certification is granted by the Swiss Official Chronometer Testing Institute, an independent organization that rigorously tests timepieces to ensure they adhere to strict performance criteria. To achieve COSC Certification, a watch must undergo a series of tests over a 15-day period, during which it is evaluated in various positions and temperatures. The primary focus is on the movement's accuracy, which must maintain a daily rate deviation of -4 to +6 seconds. This level of precision is indicative of a chronometer, a term reserved for watches that have passed these stringent tests. COSC Certification is a mark of excellence in watchmaking, signifying that a timepiece is not only a luxury item but also a highly reliable instrument. It is a testament to the craftsmanship and technological prowess of the watchmaker, ensuring that the wearer can rely on the watch for precise timekeeping. Collectors and enthusiasts often seek out COSC-certified watches for their superior quality and the assurance of performance that this certification provides.