COSC CEO Andreas Wyss’s May 2025 vision for a broader “Super-COSC” certification was to move beyond testing watch movements for precision and assess complete watches, including attributes such as water resistance and resistance to magnetic fields. That was an interview-era proposal, not a published specification. COSC announced a separately named “Excellence Chronometer Certified” certification in March 2026, but the available information does not establish whether its criteria match Wyss’s proposal.
What COSC certifies—and why independence matters
COSC is the Contrôle Officiel Suisse des Chronomètres, commonly rendered in English as the Official Swiss Chronometer Testing Institute or Authority. It is a Swiss non-profit public-interest association founded in 1973. Wyss described its origins as a joint initiative by Swiss watch brands, the Fédération Horlogère and public authorities, created to standardize chronometric testing after different cantonal observation offices used different procedures.
COSC awards chronometer certification as an official, neutral authority. For relevant mechanical wristwatch movements, its certification is based on ISO 3159. COSC says it also certifies other kinds of timekeeping instruments, including pocket watches, fixed-time devices and quartz wristwatches; those categories can use adapted specifications rather than the mechanical wristwatch criteria unchanged. COSC says mechanical wristwatches make up most of its certification work.
That independent role was central to Wyss’s argument for adapting certification. A brand can carry out its own internal testing, but he said COSC certification should remain distinct because it is administered by a neutral organization—and should provide value to consumers as well as watchmakers.
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- Swiss Made Watch
- Movement: Automatic Mido Caliber - Power reserve 80 hours - COSC Certified
- Case Size: 40mm - Band Width: 21mm - Case Thickness: 11.3mm
- Case Type: Stainless steel - See-through case back - Crystal: Sapphire crystal
- Strap: Stainless steel bracelet - Folding clasp with push-buttons
In figures published by COSC, it certified 2.1 million movements in 2025, and 39% of mechanical watches exported in 2025 were COSC-certified. Its homepage displayed a cumulative total of 57 million movements certified since its 1973 creation as of 2026. These are COSC’s own reported statistics.
What a COSC certificate means for a mechanical wristwatch
The familiar mechanical wristwatch test evaluates a movement’s rate—the amount of time it gains or loses—under different positions and temperatures. Wyss described the procedure in his May 2025 interview as a 15-day test in five positions and three temperatures, with an average daily rate between −4 and +6 seconds.
Rank #2
- Swiss Made Watch
- Movement: Automatic Mido Caliber - Power reserve 80 hours - COSC Certified
- Case Type: Stainless steel with black DLC coating and ceramic bezel - Screw-down crown
- Case Size: 43.5mm - Band Width: 22mm - Case Thickness: 14.55mm
- Crystal: Sapphire crystal with double sided anti-reflection treatment
COSC’s current explanation gives the test temperatures as 8°C, 23°C and 38°C and lists seven criteria:
- Average daily rate
- Variation in rate as a function of temperature
- Rate resumption
- Greatest difference in rates
- Difference between rates in horizontal and vertical positions
- Greatest variation in rates
- Mean rate variation
The −4 to +6 seconds-per-day window describes the mean daily rate criterion for the familiar mechanical wristwatch category; certification also evaluates the other listed aspects of rate behavior. COSC’s certification page describes test duration as 12 to 20 days depending on instrument type, while its FAQ specifies 15 days for the mechanical wristwatch process.
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- COSC Certified Chronometer
- Case Size: 39.00 mm, Band Width: 20 mm, Case Thickness: 10.98 mm
- Automatic movement, 316L solid stainless steel bracelet, Roman dial type, Date
- Water-resistant up to a pressure of 10 bar (100 m / 330 ft): suitable for short periods of recreational swimming and showering, but no diving or snorkeling.
The test is performed on the movement, so the familiar certificate does not by itself establish how the finished watch performs in every respect. It is a precision certification, not a comprehensive rating of water resistance, magnetic resistance, power reserve or other complete-watch properties.
Chronometer is not the same as chronograph
A chronometer is a timekeeping instrument certified for precision; a chronograph is a function that measures elapsed intervals. A watch can have a chronograph function and also be certified as a chronometer. The terms describe different things.
Rank #4
- COSC Certified Chronometer
- Case Size: 39.00 mm, Band Width: 20 mm, Case Thickness: 10.98 mm
- Automatic movement, 316L solid stainless steel bracelet, Roman dial type, Date
- Water-resistant up to a pressure of 10 bar (100 m / 330 ft): suitable for short periods of recreational swimming and showering, but no diving or snorkeling.
Why Wyss said the certification needed to adapt
Wyss pointed to two criticisms: that the familiar standard had changed little since 1976, and that certifying a movement rather than the cased watch can leave buyers unsure what the label says about the product they wear. The date claim is Wyss’s characterization in a 2025 interview. The official ISO record identifies ISO 3159:2009, “Timekeeping instruments — Wrist-chronometers with spring balance oscillator,” as the current edition in the record reviewed in 2026; it shows the 1976 edition as withdrawn and records that the international standard is to be revised.
His proposed response was an optional offer for interested brands alongside the existing certification—not a replacement for ISO 3159. Wyss described the ambition this way: “The goal is to certify not just movements, but complete watches. The criteria for precision will be updated to reflect the realities of modern watchmaking, but the scope will go far beyond precision alone.”
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- Movement: COSC-Certified Automatic Mido Caliber 80 Chronometer SI with silicon balance spring. In addition to its non-magnetic properties, it offers greater precision and improved shock resistance. This caliber ensures exceptional autonomy of up to 80 hours.
- This Swiss-made MIDO timepiece, designed to withstand the extreme pressures of the deep sea, is exceptionally water-resistant to 60 bar (600 m/1968 ft). Equipped with a helium valve, it guarantees safe decompression during extended dives.
- Case Type: Stainless steel with ceramic bezel and Sapphire crystal with double sided anti-reflection treatment - Screw-down crown.
- Case Size: 43.5mm - Band Width: 22mm (Tapered) - Case Thickness: 14.55mm
- Strap: Tapered Stainless steel bracelet - Folding clasp with diving extension
In the interview, he named water resistance, resistance to magnetic fields and power reserve as possible areas for broader testing. Those examples express the proposed direction; they should not be read as a confirmed list of requirements or as proof that a particular watch has passed such tests. Wyss also reported a 3%–5% failure rate in 2025; that figure is his interview-era account, not a currently independently verified rate.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What is known about COSC’s 2026 certification announcement
COSC’s homepage reported that it announced a new certification on 2026-03-18, and its certification navigation calls it “Excellence Chronometer Certified.” The available official information establishes the announcement and name, but not the detailed criteria or how they relate to Wyss’s 2025 proposal. It is therefore not sound to treat “Excellence Chronometer Certified” as simply another name for “Super-COSC,” or to assume it includes the specific complete-watch tests Wyss discussed.
Wyss also named Rolex Superlative Chronometer and Omega/Tudor Master Chronometer as examples of competing certification models. Those labels should not be ranked against COSC’s familiar movement certification—or against the proposed Super-COSC—without comparing current primary specifications for the tested object, criteria, protocol and administrator. The available information does not establish an apples-to-apples comparison of those schemes.
What buyers should check on a specific watch
COSC says certification results belong to its brand clients and that certification is optional. A COSC label is therefore not a blanket claim about every watch from a brand, or even every watch in a model family. Check the exact reference and ask the brand what was certified and which standard or criteria apply.
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- Confirm whether the claim concerns the movement or the complete watch.
- Ask which certification name and test criteria apply to that specific model.
- For claims about water resistance, magnetism or power reserve, check the brand’s specifications separately unless the applicable certification requirements explicitly cover them.
The useful distinction is between what the familiar COSC mechanical wristwatch certificate establishes—tested precision behavior for a movement—and what a broader complete-watch certification might establish. For the latter, the name alone is not enough: the criteria for the particular certification need to be known.
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