Watch Glossary

Official document certifying watch meets specified precision standards.

Official document proving watch movement meets chronometer precision standards

Official COSC certification grade indicating movement precision within specific tolerances

Set of rigorous testing criteria ensuring exceptional timekeeping precision.

Degree to which watch maintains precise and consistent timekeeping.

Contrôle Officiel Suisse des Chronomètres - Swiss official chronometer testing institute

Chronometer standard: -4 to +6 seconds per day maximum variation.

Extreme altitude testing verifying chronometer performance stability

Maximum allowable variation from mean daily rate per standards.

Official Swiss quality certification for watches made in Geneva region

International standard for diver's watches quality, water resistance, and safety requirements

METAS certification for watches exceeding traditional chronometer standards

Swiss federal metrology institute certifying ultra-precision chronometer watches

Official verification that watch movement meets specific Swiss quality and precision standards

Manufacturer's declared acceptable rate range and accuracy tolerance.

French name for Geneva Seal, Swiss quality and craftsmanship hallmark certification

Standardized procedures by COSC for evaluating chronometer precision and reliability

Maximum allowed variation in seconds per day certified by COSC standards

ISO standard measurement of watch's ability to resist water penetration at depth