Only very few establishments in the world are still accredited to issue certificates officially attesting to the chronometric quality of watches submitted for tests. Veritable “keepers of the flame” of precision watchmaking, these chronometric observatories are to be found in countries where the measurement of time has been elevated to the level of an art form down the centuries. Switzerland came first, followed by France, Germany and England which all acquired Observatories at the end of the 19th century so that they too could certify the quality of the timepieces produced on a national level.
A marvellous tool dedicated to the study of science and the universe, chronometric certification and ultimately the dissemination of learning, the Observatoire National de Besançon, with its rich scientific heritage, has become a world standard-setter in the study of time-frequency. The only French institution accredited to test and officially certify chronometers, its certification department is currently enjoying a true renaissance, not least thanks to the Leroy workshops which submit all their chronometers for testing to the institution.
Pieces submitted as complete watches ready for delivery undergo tests for 16 days consecutively in 5 different positions and under temperatures ranging from 8°C to 38°C.The battery of tests to which the watches are subjected day after day comply with the ISO 3159 international standard which tolerates only the tiniest of variations, set at a range from minus 4 to plus 6 seconds in average daily operation. Once these criteria are satisfied, each Leroy chronometer is hallmarked with the famous Viper's Head and receives its individual numbered certificate, issued to the owner of the watch.