The Contrôle Officiel Suisse des Chronomètres, the Swiss body that tests watch movements and certifies those that pass as chronometers.
COSC independently tests timekeeping precision and awards chronometer certification to pieces that meet its requirements. Certification concerns the tested piece, so it is a specific precision claim rather than a general description of a brand’s craftsmanship. Its movement-testing process includes identification checks and measurements under controlled conditions. COSC also has a separate Excellence Chronometer Certified process for complete watches, making the certification concerned an important detail when describing a product. Chronometer certification and chronograph functionality answer different questions. The former concerns tested timekeeping performance, while the latter provides a mechanism for measuring elapsed time.
In job listings
A chronometer certificate is more often a matter for product knowledge than a job requirement. Watch advisors may be asked what the certificate tests, while a watchmaker works with the same accuracy standards at the bench. Search local jobs for “watchmaker”.
