Swiss precision: the COSC. Instructions for use (part 3)

Entry requirements

1. Both COSC-certified movements and COSC-certified pieces must meet Swiss Made criteria and the brand that produces them must be registered at a national intellectual property institute that provides protection on Swiss territory.

2. Submitted movements must meet Swiss Made criteria, which means they must have been produced or bought, and assembled in Switzerland. It is crucial to read the federal Ordinance that specifies the conditions for watch movements to be attributed the Swiss Made label (in French):

3. All candidate movements must be physically deposited for a maximum of twenty-one days at one of the three BOs in full knowledge that under the ISO 3159 standard a series of compulsory tests must be carried out over a period of at least sixteen days, including one day for preparation.

4. According to an added clause in the COSC’s technical rules, a chronometer movement must feature a permanent second display.

5. Each submitted movement must belong to one of the following four categories: (1) wristwatch with spring balance, (2) pocket watch with spring balance, (3) fixed timepiece (marine chronometers, for example), or (4) quartz movement.

6. Movements must undergo a fifteen-day test in five positions and at three temperatures (8° C, 23° C et 38° C): left crown, top crown, bottom crown, visible dial, back dial and verification of some mechanism’s additional functions (i.e. date, chronograph, and so on).

Conditions for certification of mechanical movements

Movements are measured and wound 350 days a year in the three BOs. Each BO can test between 30,000 and 40,000 movements per day. The 16-day tests are carried out non-stop – including Sundays and public holidays. The measurement determines the difference between the drift of the sweep seconds in the candidate watch and a time reference delivered by a timeserver. The latter is composed of three atomic watches (2 set on rubidium GPS time and 1 set on internet time) and its residual error is inferior to 1 second in 300 years.

The difference between two consecutive states in 24 hours enables to establish the pieces’ daily rate. This will later provide the basis on which the calculation of the seven criteria fixed by the standard can be carried out.

What does the standard stablish?

1. It is essential for a piece to meet seven criteria: mean daily rate, mean variation in rates, greatest variation in rates, difference between the rates in horizontal and vertical positions of the watch, greatest deviation in rates, variation in rate as a function of temperature, and resumption of the rate.

2. Minimum requirements in seconds per day (s/d) for category 1 (movements with less than 20 mm in diameter)mean daily rate= -4 / +6

• mean variation in rates= 2
• greatest variation in rates= 5
• difference between the rates in horizontal and vertical positions of the watch= -6 / +8
• greatest deviation in rates= 10
• variation in rate as a function of temperature= ± 0.6
• resumption of the rate= ± 5

3. Minimal requirements in seconds per day (s/d) for category 2 (movements with less than 20 mm in diameter)

• mean daily rate= -5 / +8
• mean variation in rates= 3.4
• greatest variation in rates= 7
• difference between the rates in horizontal and vertical positions of the watch= -8 / +10
• greatest deviation in rates= 15
• variation in rate as a function of temperature= ± 0.7
• resumption of the rate= ± 6

Breitling’s distinctive feature

Every single piece the brand produces is systematically submitted to the COSC tests before being commercialized. The COSC has even had to implement a regulation in terms of quartz movements. The analysis of the COSC’s annual reports gives a full picture of the watches produced by the discreet brand from Granges.

Movements or assembled watches?

Some regret that, for the sake of efficiency, it is often movements rather than assembled pieces that are tested by the COSC. Only the BO in Bienne has the means to test assembled watches under the same conditions as movements only. “Our three BOs have the means to test assembled watches and we are the first to deplore the fact that Swiss watchmakers don’t ask to test assembled pieces more often”, answers Andreas Wyss, COSC director, from the headquarters in La Chaux-de-Fonds.