Automated measurement of accuracy

COSC certifications

COSC offers two levels of certification. The first, based on the ISO 3159 standard and applied since 1976, forms the foundation of precision for Swiss Made watches: it awards the "Certified Chronometer" label.

The second level, conceived as an evolution of the current standard, addresses contemporary challenges and highlights the expertise of watch manufactures. It grants the "Excellence Chronometer Certified" title, with the objective of testing finished watches under conditions close to real-life wear.

Together, these certifications guarantee precision and reliability, from the heart of the movement to the wrist.

Chronometer Certified

The historic standard: based on ISO 3159 (in force since 1976).

The iconic label of Swiss mechanical precision.

  • Generally tested on the movement

  • Precision: (-4) to (+6) seconds per day

  • Tested in 5 positions

  • Tested at 3 temperatures: 8°C, 23°C, and 38°C

Excellence Chronometer Certified

The next level: tested on the finished watch, according to a COSC protocol.

The certified watch, as you wear it.

  • Tested in 6 semi-dynamic positions to simulate real-life wear

  • Enhanced precision: (-2) to (+4) seconds per day

  • Magnetic resistance tested at 200 Gauss

  • Checking the power reserve communicated

As Time goes by