Watch Glossary
1104 horological terms explained
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C.O.S.C. CertificateCertification
Official document proving watch movement meets chronometer precision standards
Chronometer RatingCertification
Official COSC certification grade indicating movement precision within specific tolerances
Chronometer StandardCertification
Set of rigorous testing criteria ensuring exceptional timekeeping precision.
Chronometric AccuracyCertification
Degree to which watch maintains precise and consistent timekeeping.
COSCCertification
Contrôle Officiel Suisse des Chronomètres - Swiss official chronometer testing institute
COSC ToleranceCertification
Chronometer standard: -4 to +6 seconds per day maximum variation.
Cosmic Ray TestingCertification
Extreme altitude testing verifying chronometer performance stability