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Swiss official chronometer testing

In 1973, the Swiss Watch Industry Federation and five horological cantons set up the Swiss Official Chronometer Testing Institute (COSC) tasked with the observation of chronometers and the issue of chronometer certificates.

Only the three COSC offices are authorised to issue the official document guaranteeing the fact that a timepiece is accurate enough to qualify for the chronometer designation. They are capable of handling between 30,000 and 40,000 movements a day. Each movement is physically present on their premises and only a movement which complies with the Swiss made criteria can undergo the test. This testing lasts for fifteen days, in five positions and at three different temperatures between 8° and 38°C.

Moreover, applications for certification can only be presented if the watch case in which the movement will be fitted is also Swiss made. Movement suppliers must therefore name the user of the units which they submit for testing.

The COSC certificate is a label that is highly appreciated by consumers as evidence of a deliberate and exacting approach on the part of the manufacturer.