COSC

ChronometerChronometer Certificatechronometer certificationContrôle Officiel Suisse des ChronomètresCOSC (Official Swiss Chronometer Testing Institute)Precision testing
The Contrôle Officiel Suisse des Chronomètres (COSC), the Official Swiss Chronometer Testing Institute, is the institute responsible for certifying the accuracy and precision of Swiss watches.wikipedia
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Observatory chronometer

chronometer
At one time the French provided similar large scale testing at the Observatory at Besançon, however, today only a very few watches are currently tested there and carry the accolade "Observatory Chronometer".
The observatory testing regime typically lasted for 30 to 50 days and contained accuracy standards that were far more stringent and difficult than modern standards such as those set by COSC.

Seiko

K. HattoriHattori SeikoLorus
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.
The new caliber also met the Grand Seiko Standard, a chronometer certification that the company claims to be more strict than the Chronometer Certificate in Switzerland.

Rolex

TudorRolex watchRolex SA
The Saint-Imier and Biel laboratories are almost entirely devoted to testing Rolex movements.
In 2005, more than half the annual production of watches certified by Contrôle Officiel Suisse des Chronomètres (COSC) were Rolexes.

Chronometer watch

chronometerchronometerscertified
Founded in its current form in 1973, the COSC is a Swiss non-profit organization that tests chronometers that are Swiss Made.
In Switzerland, only timepieces certified by the Contrôle Officiel Suisse des Chronomètres (COSC) may use the word chronometer on them.

Besançon Astronomical Observatory

Besancon ObservatoryBesanconBesançon Observatory
At one time the French provided similar large scale testing at the Observatory at Besançon, however, today only a very few watches are currently tested there and carry the accolade "Observatory Chronometer".
The tolerances for error were much finer than any other standard, including the ISO 3159 chronometer standard that other testing bodies such as COSC use.

Breitling SA

BreitlingLéon Breitling
Although not all Rolex watches are chronometers, Breitling has claimed that since 2000 all of its production is COSC certified.
As part of 10th anniversary of a Breitling–Bentley partnership, the Bentley B04 GMT, B05 Unitime and B06 (based on COSC Certified Breitling Calibre B04, B05 and B06 respectively) were produced.

ETA SA

ETAETA MovementsETA S.A.
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 7750, each of which operates at 28,800 beats per hour.
The Chronometer grade must meet strict standards prescribed by the COSC.

Geneva Seal

Fleurier Quality FoundationPoinçon de Genève
Geneva's have created along similar criteria the Geneva seal.
Precision testing, however, is an option in the inspection process.

Nonprofit organization

non-profitnon-profit organizationnonprofit
Founded in its current form in 1973, the COSC is a Swiss non-profit organization that tests chronometers that are Swiss Made.

Swiss made

Swiss watchSwissSwiss watchmaking industry
Founded in its current form in 1973, the COSC is a Swiss non-profit organization that tests chronometers that are Swiss Made. The Contrôle Officiel Suisse des Chronomètres (COSC), the Official Swiss Chronometer Testing Institute, is the institute responsible for certifying the accuracy and precision of Swiss watches.

Acronym

initialismacronymsinitials
COSC is an acronym for the organization's French language name, Contrôle Officiel Suisse des Chronomètres.

French language

FrenchfrancophoneFrench-language
COSC is an acronym for the organization's French language name, Contrôle Officiel Suisse des Chronomètres.

Switzerland

SwissSwiss ConfederationSWI
COSC testing generally applies to watches manufactured or assembled in Switzerland.

International Organization for Standardization

ISOISO standardInternational Organisation for Standardisation
Notwithstanding, the normative standards are set by international agreement and are the same whether they are nominally labeled ISO or DIN standards.

Glashütte Observatory

On the other hand, the Germans have set up their own testing facility in Saxony at the Glashütte Observatory where the DIN 8319 standards, which mirror the ISO standards used by COSC, are employed.

Canton (country subdivision)

cantoncantonscanton seat
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Canton of Bern

BernCanton of BerneBerne
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Canton of Geneva

GenevaRepublic of GenevaGenevan
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Canton of Neuchâtel

NeuchâtelPrincipality of NeuchâtelNE
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Canton of Solothurn

SolothurnSOCanton Solothurn
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Vaud

Canton of VaudVDCanton de Vaud
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Federation of the Swiss Watch Industry

Federation of the Swiss Watch Industry FHSwiss watch manufacturersFederation of Swiss Watches
The organization was founded by five watchmaking cantons of Switzerland: Bern, Geneva, Neuchâtel, Solothurn and Vaud, together with the Federation of the Swiss Watch Industry (FHS).

Biel/Bienne

BielBienneBiel, Switzerland
They are in Biel/Bienne, Saint-Imier/BE and Le Locle.

Le Locle

Le Locle NELe Locle, SwitzerlandLocle
They are in Biel/Bienne, Saint-Imier/BE and Le Locle.

Omega SA

OmegaOmega WatchesLouis Brandt
Omega also has much of its production certified.