Chronometer

A chronometer which should not be confused with a chronograph is a highly accurate timepiece which has been rigorously tested for 15 days and whose performance has been measured at different temperatures and positions. For mechanical watches an accuracy  level of -5/+6 seconds per day has to be achieved before a chronometer certificate is awarded.

The test procedure which is carried out by COSC (Contrôle Officiel Suisse des Chronomètres) is expensive and quartz watches are rarely submitted for test. Among manufacturers Breitling are a rare exception in gaining certificates for their quartz watches. Certificates can be issued by the observation at Geneva and Neuchatel.