COSC
Encyclopedia
- For the state college in Connecticut, see Charter Oak State CollegeCharter Oak State CollegeCharter Oak State College is a public liberal arts college in New Britain, Connecticut and is named for Connecticut's famous Charter Oak. The college is located across Paul Manafort Drive from Central Connecticut State University...
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COSC aka C.O.S.C. is Contrôle Officiel Suisse des Chronomètres, the Official Swiss Chronometer Testing Institute, which is the institute responsible for certifying the accuracy and precision of wristwatches in Switzerland.
Background
Founded in its current form in 1973, the COSC is a Swiss non-profit organization that tests Swiss-made chronometers. COSC is an acronym for the organization's FrenchFrench language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
name, Contrôle Officiel Suisse des Chronomètres.
COSC testing generally applies to watches manufactured/assembled in Switzerland. Notwithstanding, the normative standards are set by international agreement and are the same whether they are nominally labeled ISO or DIN standards. Some German, Japanese, and even non-certified Swiss movements can surpass the normative requirements. The Japanese have largely abandoned the accolade, replacing it with in-house testing to a slightly more strict standard as with, for example, the Grand Seiko. On the other hand, the Germans have set up their own testing facility in Saxony at the Glashütte Observatory
Glashütte Observatory
Glashütte Observatory is an observatory located in Glashütte, Saxony, Germany.Hugo Müller led the way and supplied a plot of land in Dittersdorfer Weg for the construction of an observatory, which began construction when the foundation stone was set on 27 August 1906...
where the DIN 8319 standards, which mirror the ISO standards used by COSC, are employed. At one time the French provided similar large scale testing at the Observatory at Besançon
Besançon Astronomical Observatory
The Observatoire des sciences de l'Univers de Besançon is an astronomical observatory owned and operated by the Centre national de la recherche scientifique...
, however, today only a very few watches are currently tested there and carry the accolade "Observatory Chronometer."
The COSC was founded by five watchmaking cantons (administrative divisions, similar to states in the U.S.A.) of Switzerland: Bern, Geneva
Geneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
, Neuchâtel, Solothurn
Solothurn
The city of Solothurn is the capital of the Canton of Solothurn in Switzerland. The city also comprises the only municipality of the district of the same name.-Pre-roman settlement:...
and Vaud
Vaud
Vaud is one of the 26 cantons of Switzerland and is located in Romandy, the French-speaking southwestern part of the country. The capital is Lausanne. The name of the Canton in Switzerland's other languages are Vaud in Italian , Waadt in German , and Vad in Romansh.-History:Along the lakes,...
, together with the Federation of the Swiss Watch Industry (FHS)
Federation of the Swiss Watch Industry FH
The Federation of the Swiss Watch Industry FH is the Swiss watch industry's leading trade association.-History:...
. It encompasses the laboratories/observatories that had been created independently of each other from the late 19th century.
Three laboratories now test the movements submitted by individual watch manufacturers to be granted chronometer status. They are in Biel/Bienne
Biel/Bienne
Biel/Bienne is a city in the district of the Biel/Bienne administrative district in the canton of Bern in Switzerland.It is located on the language boundary and is throughout bilingual. Biel is the German name for the town, Bienne its French counterpart. The town is often referred to in both...
, Geneva
Geneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
and Le Locle
Le Locle
Le Locle is a municipality in the district of Le Locle in the canton of Neuchâtel in Switzerland.It is situated in the Jura mountains, a few kilometers from the city of La Chaux-de-Fonds....
. The Geneva and Biel laboratories are almost entirely devoted to testing Rolex
Rolex
Rolex SA is a Swiss watchmaking manufacturer of high-quality, luxury wristwatches. Rolex watches are popularly regarded as status symbols and BusinessWeek magazine ranks Rolex No.71 on its 2007 annual list of the 100 most valuable global brands...
movements. Although not all Rolex watches are chronometers, Breitling
Breitling
Breitling is a luxury brand of Swiss watches produced by Breitling SA, a private company headquartered in Grenchen, Canton of Solothurn . The company exclusively offered Certified Chronometers in all models since 2000...
has claimed that since 2000 all of its production is COSC certified. Omega also has much of its production certified. Thus, based upon the movements used by Rolex, Breitling, and Omega, the movement calibers that obtain most of the COSC certificates are the Rolex 3135 (since 1988) (and variants 3155, 3175, 3185, 4130) and 2235, the ETA 2892A2 (and variants) and Valjoux
Valjoux
Valjoux is a Swiss manufacturer of mechanical watch movements. It is known primarily for chronograph ébauche movements that are used in a number of mid- to high-range mechanical watches: The company has been a part of ETA for a number of years and is a member of the Swatch Group...
7750, each of which operates at 28,800 beats per hour.
Standards and methods
Each officially certified COSC chronometerCertified chronometer
A certified chronometer is a high-precision watch capable of displaying the seconds and which has been tested and certified by an official neutral body ....
is identified by a serial number
Serial number
A serial number is a unique number assigned for identification which varies from its successor or predecessor by a fixed discrete integer value...
engraved on its movement and a certification number given by the COSC.
Testing criteria are based on ISO 3159 which defines a wrist chronometer with spring-balance oscillator. Only movements which meet the precision criteria established under ISO 3159 are granted an official chronometer certificate. Compare ISO 3158.
Each uncased movement is individually tested for fifteen days, in five positions, at three different temperatures. The movements are fitted with a seconds hand and the automatic winding mechanisms are disengaged for the tests. Measurements are made daily with the aid of cameras. Based on these measurements, seven eliminatory criteria are calculated, each of which must be met (e.g., for movements of a diameter over 20 mm, the requirements, indicated in seconds/day, are noted in the table below). There is no ISO standard for quartz timepieces, but there is development in this field. ISO 10553:2003 specifies the procedure for evaluating the accuracy of quartz watches, individually and by lot, and the relationship between the accuracy tested and the accuracy classification given by the manufacturer. It applies to quartz watches having accompanying documents on which the accuracy classification is indicated. Nevertheless, COSC has also developed its own standard for testing quartz chronometers with eight eliminatory criteria, also noted in the table below.
| Mechanical | Quartz |
|---|---|
| Average daily rate: -4/+6 | Average daily rate at 23 °C: ± 0.07 |
| Mean variation in rates: 2 | Rate at 8 °C: ± 0.2 |
| Greatest variation in rates: 5 | Rate at 38 °C: ± 0.2 |
| Difference between rates in H & V positions: -6/+8 | Rate stability: 0.05 |
| Largest variation in rates: 10 | Dynamic rate: ± 0.05 |
| Thermal variation: ± 0.6 | Temporary effect of mechanical shocks: ± 0.05 |
| Rate resumption: ± 5 | Rate resumption: ± 0.05 |
| n/a | Residual effect of mechanical shocks: ± 0.05; 200 shocks equivalent to 100 G (981 m/s², 3,217 ft/s²) |
Measurements are compared with a time base established by two independent atomic clocks synchronized on GPS time. Not all chronometers are supplied with the report issued by the COSC as the reports are optional to the brand or maker. Each manufacturer may decide whether to reveal the results gathered during the certification process of the movement. For example, Breitling do supply all their watches with COSC Certificates (all Breitling watches since 2000 are Certified chronometers) however Rolex and Omega do not supply even their chronometer certified watches (not all their watches are certified chronometers) with the COSC certificates. Omega however can provide the COSC chronometer certificate if asked.
Observatory trials and standards before 1973
While competitive chronometer testing took place at the observatories in Neuchâtel (1866–1975) and Geneva (1873–1967), testing of large numbers of watches intended for public sale was conducted by the independent Bureaux officiels de contrôle de la marche des montres (B.O.s) established between 1877 and 1956. Between 1961 and 1973, “a chronometer [was] a precision watch, which [was] regulated in several positions and at different temperatures and which had received a certificate [from the (“B.O.)]." Collective certificates, rather than individual certificates, were usually issued. The 1961-73 standard required a mean daily rate in five positions of -1/+10. In 1973, the B.O.’s came under the C.O.S.C. which specified a daily rate of -4/+6 sec.......Only 3% of Swiss Watch production is COSC certified
Over a million official chronometer certificates are delivered each year, representing only 3% of the Swiss watch production, a proportion that underscores the exceptional nature of a chronometer. To earn chronometer certification, a movement must not only be made from the highest quality components, but also be the object of special care on part of the finest watchmakers and timers during assembly.Meaningful test or marketing gimmick?
There is a debate among watch enthusiasts as to whether the COSC chronometer certification for a Swiss watch is a meaningful test or a simple marketing gimmick. On the one hand, when a watch maker intends to submit a movement for COSC testing, they frequently employ additional jewelling (i.e. to the barrel) and better quality "ÉbaucheÉbauche
Ébauche is a term used in art to denote the first preliminary underpainting or quick sketch in oils for an oil painting. One early criticism of Impressionist painting was that its practitioners sought to elevate the status of the ébauche to the level of finished painting...
" parts (i.e. higher quality hairsprings, mainsprings, balance wheels; regulators, etc.) all aimed at the coveted chronometer certification. On the other hand, it is likely that most good quality movements on the market today are capable of being tweaked, and timed to fall comfortably within the benchmark -4/+6 average daily rate criteria of the COSC. However, movements so submitted to COSC are more likely to be submitted with better quality parts in order to be confident of a successful test, and as a consequence may be more likely to maintain better timekeeping rates over the service life of the time piece.
Therefore, some of the ″Haute Horlogerie″ Swiss Watch Manufacturers have created on 5 June 2001, ″The Fleurier Quality Foundation″ to establish new aesthetic and technical criteria dedicated to the certification of finished watches. Their certification meets a normative requirement for the market and the final customer to have a better definition of quality watchmaking, adapted to today's demands and technological advances. Geneva's have created along similar criteria the Geneva seal
Geneva seal
The Geneva Seal , Poinçon de Genève , or Genfer Siegel is the official seal of the City and Canton of Geneva, Switzerland...
Exemplar brands submitting to COSC
RolexRolex
Rolex SA is a Swiss watchmaking manufacturer of high-quality, luxury wristwatches. Rolex watches are popularly regarded as status symbols and BusinessWeek magazine ranks Rolex No.71 on its 2007 annual list of the 100 most valuable global brands...
submit by far the largest number of movements to COSC followed by Omega SA, Breitling
Breitling
Breitling is a luxury brand of Swiss watches produced by Breitling SA, a private company headquartered in Grenchen, Canton of Solothurn . The company exclusively offered Certified Chronometers in all models since 2000...
, TAG Heuer
TAG Heuer
TAG Heuer is a Swiss luxury watchmaker known for its sports watches and chronographs. It is a division of luxury goods company LVMH Moët Hennessy • Louis Vuitton. The company motto is "Swiss Avant-Garde Since 1860"...
and Panerai
Panerai
Officine Panerai Marketing e Communicazioni Srl, a wholly owned subsidiary of Compagnie Financière Richemont S.A., designs, manufactures, markets and sells watches under the Officine Panerai brand through authorized dealers and company-owned boutiques worldwide. Giovanni Panerai founded Officine...
.
. Breitling
Breitling
Breitling is a luxury brand of Swiss watches produced by Breitling SA, a private company headquartered in Grenchen, Canton of Solothurn . The company exclusively offered Certified Chronometers in all models since 2000...
submit all movements for certification but other manufacturers only submit certain models.
Certification in perspective
Fine regulation and chronometer characteristics of a watch can be destroyed in seconds by a rough and inexperienced hand.Considering the fact that mechanical watches are almost never used for real timekeeping and navigation anymore, and that practically any quartz watch is vastly better in accuracy, certification may be considered a historic relic by some, but it verifies the accuracy and quality of a mechanical movement (though quartz is almost always more accurate, mechanical movements are preferred by some watch collectors/enthusiasts).
See also
- British Horological InstituteBritish Horological InstituteThe British Horological Institute is the representative body of the horological industry in the United Kingdom.-History:...
- Geneva sealGeneva sealThe Geneva Seal , Poinçon de Genève , or Genfer Siegel is the official seal of the City and Canton of Geneva, Switzerland...
- Science and technology in SwitzerlandScience and technology in SwitzerlandScience and technology in Switzerland play an important role in economy as very few natural resources are available in the country. The Swiss National Science Foundation, mandated by the Federal government, is the most important institute promoting scientific research.The raw output of scientific...