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COSC - An External Referee

COSC An External Referee

Increasingly, high-end firms seek chronometer certification from the COSC.

WORLDTEMPUS - 2 November 2010

Jonathan Bues

Few would argue that accuracy is an unimportant quality for a watch. However, every day consumers purchase mechanical watches that offer no basic assurance of horological precision. There are, however, several firms that capitalize on the services of the independent Contrôle Officiel Suisse des Chronomètres (COSC) as a guarantor of their watches' fundamental accuracy within -4 to +6 seconds per day.


Last year at the SIHH, Roger Dubuis, a firm that has famously employed the aesthetic standards of the Geneva Seal, announced that it would add a second layer of external oversight by also submitting movements to the COSC.

For Claude Vuillemez, the COO of Roger Dubuis, the appeal of COSC certification is obvious.

“We are a young manufacture,” Vuillemez told Worldtempus, “and to get recognition we are looking to external referees like COSC on chronometry and Timelab on functionality to validate our technical expertise.”

Breitling has cultivated its image around the fact that it is first and foremost a maker of chronometer-rated instrument watches. Indeed, every Breitling timepiece, quartz or mechanical, is also a COSC-certified chronometer.


“Like in aviation, where every instrument needs to be certified, COSC is an independent laboratory checking the precision of every single Breitling movement for 15 days in 5 positions and at 3 different temperatures,” said Breitling executive vice president Jean-Paul Girardin.

Who's Who?

The COSC releases annual lists ranking the brands receiving the most certifications, with Rolex, Omega and Breitling perennially occupying the top three spots.

The global recession contributed to a shake-up of the list in 2009, with Ball Watch, a relatively small producer, breaking into the top ten (at number eight) for the first time in its history — with 15,455 certifications.

Jeffrey Hess, president of Ball Watch in North America, attributes his firm's rise not so much to any specific actions taken by the Swiss watch company with American roots, but to cutbacks in production at some competitors.

While 2009 was difficult for much of the industry, Hess says it was actually a fairly good year for Ball Watch — which led to no reduction in production of certified chronometers.

Ball Watch has another reason for its interest is chronometer certification. Historically, the firm submitted pocket watches to the U.S. Bureau of Standards as a measure intended to ensure the accuracy of its famous railroad chronometers. These were the precise timekeepers used by railroad engineers to avoid potentially disastrous collisions. Hess sees the modern COSC as an extension of this legacy.


At the very least, a modern COSC-certified wristwatch will help its wearer make his or her train on time — as Webster C. Ball originally intended.

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