Founded in 1973 the Official Swiss Chronometer Testing Institute (COSC) is responsible for certifying the accuracy and precision of wristwatches in Switzerland.
The tests are based on ISO standards and lasts 15 days. They are designed to check the accuracy of the watch in all types of positions and conditions. The benchmark requirement for accuracy is a daily rate of −4/+6 sec.
If the watch passes the tests it can be certified as a “chronometer”
The COSC was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).