COSC Introduces New Standard: Excellence Chronometer Certified

In a moment of celebration annual commemoration The 50th ISO 3159 standard, Contrôle Officiel Suisse des Chronomètres (COSC) officially introduced a new certification, namely Excellence Chronometer Certified. This certification is higher than Timekeeper and designed to respond to developments in modern horological technology as well as the increasingly high expectations of watch manufacturers and consumers. Want to know more? Check out the complete information below!

Get to Know the New Standard of Excellence Chronometer Certified

As an independent institution that has been a reference for certification for decades timekeeper Switzerland, COSC emphasized that this new standard does not replace certification timekeeper which has existed. In contrast, Excellence Chronometer Certified exists as an expansion and strengthening of the standard, with a testing approach that is more comprehensive and relevant to real use conditions. In this standard, the testing process is carried out over four days, while strengthening performance requirements through:

1. Tested on Finished Watch (not movement)

Different from conventional chronometer certification that tests movement before being assembled inside caseExcellence Chronometer Certified performs hands-on testing on fully finished watches. This approach allows COSC to assess overall clock performance, including impact case, callneedles, and other components on time accuracy. With this method, the test results are considered to be more representative of the performance of the watch when used daily by the wearer.

2. Tighter Accuracy Tolerance (-2 to +4 Seconds per Day)

The new standard also tightens daily time deviation tolerances. While standard COSC chronometers allow deviations of up to -4/+6 seconds per day, the Excellence Chronometer Certified sets stricter limits of -2 to +4 seconds per day. This tightening of tolerances emphasizes COSC’s focus on high precision, while also responding to the demands of modern consumers who are increasingly critical of the accuracy of mechanical watches.

3. Magnetic Resistance Test up to 200 Gauss

In everyday use, watches are often exposed to magnetic fields from electronic devices such as cellphones, laptops or speakers. Therefore, this new certification requires magnetic resistance testing up to 200 Gauss. This test ensures that the watch continues to work accurately when exposed to mild magnetic fields commonly encountered in daily activities, without significant disruption to the engine’s performance.

4. Verify Power Reserve

The last step is to verify the power reserve according to the manufacturer’s claims. Through this new certification, COSC will ensure that the proposed watch is truly capable of achieving duration power reserve stated by the brand.

Reportedly, the transition to the new Excellence Chronometer standard has begun. A number of new technologies have been integrated into the COSC process since the start of this year as part of preparations for implementation of the standard, along with testing equipment updates.

Initial trials are scheduled to begin in March 2026, while COSC will introduce the new procedure more widely to the public at the Watches & Wonders event in April 2026, via the LAB exhibition which has been part of the event for the past few years. COSC estimates the rollout phase will begin in October 2026, at which point brands will be able to apply for certification for case-mounted watches through this new process.

That is the information regarding the new Excellence Chronometer Certified certification. The presence of this standard is an important step in setting benchmarks for watch precision and performance. Let’s wait for further developments and the brands that will adopt this certification.

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