The Contrôle Officiel Suisse des Chronomètres or COSC (The Official Swiss Control Office for Chronometers) reported record figures for 2007. The number of certificates registered in 2007 was up 13.3 per cent from 2006 making that a total number of 1,538,676 registrations.
The top three companies applying for registration were Rolex with 728,255 certificates, Omega with 341,161 and Breitling with 222,650.
Who is the COSC? C.O.S.C. was founded as it is currently known in 1973. It is a Swiss non-profit organization that tests Swiss-made chronometers.
Who founded COSC? COSC was founded by five watchmaking regions of Switzerland: Bern, Geneva, Neuchatel, Solothurn and Vaud, in conjunction with the Federation of the Swiss Watch Industry (FHS). It includes the laboratories/ observatories that were created independantly of each other from the late 1800's.
What is the role of COSC? COSC tests the movements of timepieces submitted by individual watch manufacturers to be granted the status of chronometer.
Where is COSC located? COSC have testing laboratories in three different locations: Biel/Bienne, Geneva and Le Locle. The Laboratories in Geneva and Biel are almost completely dedicated to testing Rolex movements.
Which movements calibres obtain most of the COSC certificates? The Rolex 3135 (since 1988) variations of which are 3155,3175,3185,4130; Rolex 2235; the ETA 2892A2, and its variants; Valjoux 7750. Each of these movements operate at 28,800 beats per hour.
Bretling claims that all its watches that have been manufactured since 2000 are COSC certified, Rolex and Omega watches have a large selection of their watches which are COSC certified.
Each movement is individually measured. Any watch with the denomination "chronometer" is provided with a certified movement.
The perfect accuracy of a chronometer can be destroyed with rough handling and little maintenance
There is an ongoing debate, by watch enthusiasts whether the COSC Certification is a significant test or simply a marketing gimmick? A watch maker proposing to submit a movement for COSC testing, they add additional jeweling (i.e. to the barrel) and superior quality "assortment" parts - better quality hairspring, mainsprings, balance wheels, regulators and so on). The aim is to obtain the highly regarded COSC Chronometer Certification. Alternatively, many watch enthusiasts believe that with today's innovations utilized in watch making, most high-end, good quality movements are capable of being adjusted and timed so that they will fall between the COSC criteria of -4/+6 average daily rate. Movements that are presented are more likely than not, presented with better quality parts, and as a result may be less likely to maintain better timekeeping rates over longer periods.