Master Chronometer (METAS)
A certification developed by Omega and the Swiss federal metrology institute METAS in 2015. Tests cased-up watches across eight criteria including 15,000-gauss magnetic resistance, more demanding than COSC alone.
Master Chronometer is a certification developed jointly by Omega and the Swiss federal metrology institute METAS (Eidgenössisches Institut für Metrologie) and introduced in 2015. It tests complete, cased-up watches rather than bare movements, and applies eight criteria more demanding than COSC alone.
What Master Chronometer tests
Each watch must pass eight tests over 10 days:
- Magnetic resistance at 15,000 gauss for both the movement and the cased watch. This is the headline differentiator — most chronometers can be magnetised at 1,000 to 1,500 gauss.
- Accuracy of 0 to +5 seconds per day on the cased-up watch.
- Accuracy in six positions with strict tolerances.
- Accuracy at multiple power-reserve states (full, partial, low).
- Power reserve verified to spec.
- Water resistance verified.
- Magnetic-field rate deviation while under magnetic exposure.
- Functional consistency across temperature.
A watch that passes receives a numbered Master Chronometer certificate. METAS, not Omega, is the certifying authority — Omega cannot certify itself.
Why magnetic resistance matters
Modern environments are full of magnetic sources: phones, tablets, induction cooktops, bag closures, MRI machines. A magnetised movement runs fast (sometimes by minutes per day) and requires demagnetisation as a service step. 15,000 gauss resistance is roughly 15x what standard chronometers handle and makes the watch functionally immune to everyday magnetic exposure.
Omega's Co-Axial Master Chronometer movements achieve this through non-ferrous silicon hairsprings and various non-magnetic alloy components. Rolex has its own anti-magnetic Parachrom hairspring but does not formally certify to 15,000 gauss.
Brands that use Master Chronometer
- Omega is the primary brand. The Seamaster, Speedmaster, Constellation, and most current production carry Master Chronometer certification. Older Omega movements (pre-2015) typically have COSC only.
- Tudor introduced its own METAS-certified Master Chronometer line in 2021 (the Black Bay Pro and selected Black Bay 58 variants), aligning with parent Rolex's broader anti-magnetic positioning.
The certification is open to other brands but adoption beyond Omega and Tudor remains limited.
Practical implications
- Resale value. Master Chronometer adds 5 to 10 percent over comparable non-Master Chronometer references in the same brand.
- Service intervals. Master Chronometer watches typically warrant 8 to 10 years instead of the standard 5 years.
- Documentation. The METAS certificate ships with the watch and belongs in the full set. Missing certificates can sometimes be replaced through Omega service for a fee.
Related: cosc, caliber, water-resistance, manufaktur-service.