How accurate should a chronometer be?
A chronometer is essentially an extremely accurate timepiece. It can be either a clock or a watch. To classify as a chronometer, a timekeeping device – be it a clock or watch – must conform to certain standards and pass rigorous tests. The internationally accepted body which makes maintains these standards is based in Switzerland. The Swiss Official Chronometer Control body is known in French as the Controle Officiel Suisse des Chronometres and is hence called the COSC. According to COSC a chronometer is a high-precision watch capable of displaying the seconds and housing a movement that has been tested over several days, in different positions and at different temperatures, by an official neutral body (COSC). Each movement is individually tested for several consecutive days, in 5 positions and at 3 temperatures. Each movement is individually measured. Any watch with the denomination “chronometer” is provided with a certified movement.
