STEP
01
Day 01
THE ARRIVAL OF THE WATCHES
Reception of the watches
Verification of the engraved number
Placement in a dedicated individual carrier
Resting period of 12 hours at 23°C
"Excellence Chronometer Certified"
A hallmark of quality and precision
The "COSC Excellence Chronometer" certification pushes beyond the traditional boundaries of watchmaking certification by integrating real-life conditions of use. As the world evolves, expectations for precision and robustness evolve with it. This label reflects a contemporary approach: a watch’s performance is measured not only in the laboratory, but also as it is worn on the wrist.
More than a simple label, "COSC Excellence Chronometer Certified" is a testament to the expertise of the manufactures, their rigor, and their commitment to innovation. It guarantees that the watch has been designed with the highest standards and tested without compromise.
The new certification builds on what has defined COSC’s strength since its inception. For fifteen days, movements are tested according to the seven criteria of the ISO 3159 standard. Once certified as chronometers, they return to the manufacture to be cased.
The finished watches then undergo four days or more of additional evaluation to be awarded the "Excellence Chronometer Certified" title.
One hundred percent of the watches are tested: COSC does not operate by sampling. This rigorous requirement guarantees the excellence of every timepiece.
The stages of certification
Understanding certification
STEP
02
Day 02
SIMULATED WEAR AND PRECISION TESTING
Winding of the watch to 100%
Optical measurement of initial precision
Simulation of wear in 6 semi-dynamic positions over 24 hours
Precision measurements with a chronometric deviation between (-2)(+4) seconds per day
STEP
03
Day 03
A QUEST FOR MAGNETIC FIELD RESISTANCE
Winding of the watch to 100%
Demagnetization
Exposure to a magnetic field of 200 Gauss, oriented 3H–9H
Verification of operation under magnetic field (no stoppage under exposure)
Evaluation of the watch’s precision, confirming a chronometric deviation within ±10 seconds per day.
Demagnetization
This process is repeated in two other orientations: 6H–12H and Dial Up – Dial Down
STEP
04
Days 04 +
POWER RESERVE VERIFICATION
Winding of the watch to 100%
Verification of the watch’s operation after the power reserve duration stated by the brand
STEP
05
Days 05 +
ANALYSIS OF THE RESULTS
Calculation of compliance with the 8 certification criteria
Issuance of the "Excellence Chronometer Certified" certificate
Return of the watches to the clients
Our 8 certification criteria
To qualify for this title of excellence, watches must meet eight rigorous criteria. At the end of the full test cycle, precise calculations determine whether a watch may be certified. Failure to comply with even one of these criteria is sufficient to disqualify the watch from the prestigious "COSC Excellence Chronometer Certified" title.
Chronometric deviation between (-2)(+4) seconds per day after simulated wear in 6 positions over 24 hours
Proper operation of the watch at the end of the power reserve duration stated by the brand
Proper operation of the watch during exposure to a magnetic field of 200 Gauss: orientation 3H–9H
Rate deviation after exposure to a magnetic field of 200 Gauss within ±10 seconds per day: orientation 3H–9H
Proper operation of the watch during exposure to a magnetic field of 200 Gauss: orientation 6H–12H
Rate deviation after exposure to a magnetic field of 200 Gauss within ±10 seconds per day: orientation 6H–12H
Proper operation of the watch during exposure to a magnetic field of 200 Gauss: orientation Dial Up – Dial Down
Rate deviation after exposure to a magnetic field of 200 Gauss within ±10 seconds per day: orientation Dial Up – Dial Down
THE CERTIFICATION
Discover "Chronometer Certified"
Discover the excellence of the COSC-certified chronometers. Learn more about precision and the "Chronometer Certified" certification process.
