The irreplaceable objectivity of independant testing organisations
The Swiss Official Chronometer Testing Institute (COSC) certifies the precision of the movements. This non-profit official body is state recognised and its official watch rating offices are two laboratories located in Biel and Le Locle – each of which has earned accreditation as a “Swiss Calibration Service” laboratory granted by the Swiss Accreditation Service
What exactly is a chronometer?
The term chronometer is often wrongly applied to timekeeping instruments fitted with an additional mechanism that may be set in motion by pushbuttons to enable measurement of the duration of an event.
Such an instrument is in fact a chronograph or chronoscope. It may of course be chronometer-certified, provided it meets the criteria set for the standard.
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).
The testing procedure
In accordance with the ISO 3159 norm, it conducts an exhaustive examination of all calibres that are submitted to it via a battery of tests lasting 16 days. During these 384 hours, the precision of mechanical movements is measured in five positions and at three different temperatures (8°C, 23°C and 38°C). Whatever these conditions, the movements must maintain a precision ranging between -4 and +6 seconds per day for calibres measuring more than 20 mm in diameter, and between -5 and +8 seconds for smaller calibres. Movements meeting the precision criteria are granted a chronometer certificate – a privilege reserved for only 5% of total watch production in Switzerland.
The level of reliability and quality reached by L.U.C calibres enables them all to earn chronometer certification from the Swiss Official Chronometer Testing Institute (COSC).