User manual
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COSC (Contrôle Ofciel Suisse des Chronomètres) is the Ofcial
Swiss Chronometer Testing Institute responsible for certifying
both accuracy and precision of wristwatches in Switzerland.
Certication follows exhaustive testing. In achieving
the coveted status of Certied 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 nest horologists
and technicians as it is painstakingly assembled.
Only movements which meet the precision criteria
are granted an ofcial certicate. Each uncased
movement is individually tested for fteen days,
in ve positions, at three different temperatures.
Movements are tted 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.
COSC CERTIFICATION
THE COSC CERTIFIED CHRONOMETER