In this circumstance, the Thermo Compensated Movement is being utilized in these watches. The thermo compensated movement is made by ETA 251.233 and is comprised of 27 jewels. This fact differs from most quartz movements which generally do not have any jewels in the movement. The ETA 251.233 in entirely Swiss Made. These are the most accurate certified quartz caliber movements currently available; the movement maintains a -15 seconds per year. Due to their exceptional accuracy, thermo compensated quartz watches take accuracy in performance to another level in timekeeping.
To gain chronometer status, watchmakers submit their Swiss movements to COSC, an independent, non-profit making watch accuracy verification organisation based in Geneva, to be tested against the international standards of ISO and DIN.
Certification follows exhaustive testing. In achieving the coveted status of Certified Chronometer, a movement must not only be made from the highest quality components, but also be the object of special care on part of the finest horologists and technicians as it is painstakingly assembled.
Only movements which meet the precision criteria are granted an official certificate. Each uncased movement is individually tested for fifteen days, in five positions, at three different temperatures.
Movements are fitted with a second hand for tests and measurements are made daily with the aid of cameras. Based on all of these measurements, seven eliminatory criteria are calculated, each of which must be met.
The exacting and rigorous nature of the COSC certification process means that the achievement of Certified Chronometer status is extremely rare. In fact, of all the watches produced in Switzerland each year, just 3% bear the coveted COSC ‘bulletinde marche’ or certificate of watch performance.Which is why, when you read the words ’Certified Chronometer’ on a Swiss watch you can be sure that the movement behind the elegant dial is a rare example of fine Swiss watchmaking which is accurate, precise… and extremely rare.