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Looking at COSC’s new Excellence Chronometer certification

- by Preetika Mathew

—While there are plenty certifications in the watch industry today, there are few that are as popular and as commonly used as the one issued by the Contrôle Officiel Suisse des Chronomètres (COSC) or the Official Swiss Chronometer Testing Authority for a movement.

COSC proves the reliability and high precision of a movement, both quartz and mechanical, deeming it a chronometer. To obtain this certification, the movement, specifically of a Swiss watch, is subjected to a series of tests that ascertain its precision under different temperatures and positions for 12 to 20 days, measured against seven criteria. Mechanical movements are tested in accordance with the ISO 3159 standard, while quartz movements follow internal requirements inspired by this standard but adapted to their specific features.

The COSC certification is a benchmark in the Swiss watch industry, and has been so since 1973 when it was established by Swiss five cantons—Bern, Geneva, Neuchâtel, Solothurn, and Vaud—and the Federation of the Swiss Watch Industry to create an independent and universally recognised institution to certify the precision of Swiss watch movements. Using a wide range of tests that cover the movement's precision from every angle (refer box on P. 50), COSC is an industry benchmark. Consisting of three laboratories in Bienne, Le Locle, and Saint-Imier, COSC's 164 highly-trained employees certify over 2 million movements and watches each year for over 60 brands, including Rolex, Tudor, Breitling, Omega, Zenith, Chopard, Tissot, Bvlgari, and more. Its guidelines have also remained unchanged since it was instituted. Until this year.