the Contrôle Officiel Suisse des Chronomètres, is one of the Swiss organisations responsible for awarding the title of Chronometer to a watch movement. To qualify, it must lose at most up to 4 seconds or gain up to 6 seconds per day. The organisation uses optical machines equipped with high-speed digital cameras to measure precision and deviation, which is why the watch requires a running seconds hand. Importantly, only the movement itself is tested before it is placed into the case. Recently, the organisation introduced its ‘Excellence Chronometer’ standard, tightening accuracy further to between -2 and +4 seconds per day.