« Wristwatches for Lovers of Precision »
Taken literally, the word chronometer means little more than a device for measuring time. Yet for watch connoisseurs, the term has a very special ring to it. A chronometer is not just any watch. It is an exceptionally precise timepiece whose performance has been tested and confirmed by a corresponding certificate.
Precision Timepieces for Navigation at Sea and in the Air
The need for a watch with especially accurate timekeeping first arose in seafaring. Accurate timekeeping was a prerequisite for precisely determining longitude, which in turn made it possible to fix a position with a degree of accuracy never achieved before. Aviation, too, relied on high-precision mechanical watches for navigation until the invention of the quartz watch.
Incidentally, early marine chronometers mostly came from French or English workshops, but today a mechanical chronometer – particularly a certified wristwatch – is usually a Swiss watch. The first Swiss chronometers were made primarily in the manufactures of Abraham Louis Breguet and Ulysse Nardin. Today, of course, mechanical precision timepieces are used for navigation only in exceptional cases. For lovers of fine watches, however, an especially accurate mechanical watch has lost none of its fascination.
COSC Certification – the "Knighthood" for a Swiss Watch
Because of the particularly high demands placed on chronometers, the need arose early on to subject their accuracy to special testing and to document it with a certificate. In Switzerland, this role is filled by the Contrôle Officiel Suisse des Chronomètres (COSC). In its current form, the Swiss chronometer testing institute is an association under Swiss law, supported by the five cantons of Bern, Geneva, Neuchâtel, Solothurn, and Vaud – also known as the "watchmaking cantons" – as well as by the Federation of the Swiss Watch Industry FH.
The institution, headquartered in La Chaux-de-Fonds, was formed in 1973 through the merger of various private and semi-public laboratories. Even though its name contains the word "official" and several cantons are members of its supporting association, COSC is neither a public-law body nor a government-supervised testing authority. Rather, it serves as a voluntary self-regulatory organization of the watch industry and is recognized as a non-profit organization.
To be called a chronometer and to carry the prestigious word "Chronometer" on its dial, a wristwatch must pass a standardized testing procedure at COSC. In principle, it makes no difference whether the timepiece is a wristwatch, a marine chronometer, or another type of watch. Only after the test has been successfully completed does the manufacturer receive the coveted quality certificate for that watch.
How Does COSC Test Chronometers?
COSC tests the accuracy of the watches submitted by manufacturers for certification at three different temperatures and in five different positions. The reason is that at sea and in aviation in particular, it is essential that neither changes in position nor fluctuations in temperature impair the precise running of the watches used for navigation. Because the testing procedure is relatively elaborate, it takes a total of 15 days to complete the chronometer test for a mechanical watch.
During testing, the rate deviation is measured every 24 hours, and the movement is rewound and reset before testing continues in the next position. If the wristwatch has complications – such as a chronograph function – these are activated on the tenth day of testing to determine how they affect the accuracy of the caliber. Once testing is complete, the certificate is issued, containing information on seven different test criteria. These include the mean daily rate, the mean variation in daily rates, the greatest variation in rates, and the thermal coefficient, which indicates the rate deviation per degree Celsius. In addition to mechanical watches, watches with quartz movements can also undergo chronometer testing. In this case, the testing procedure takes 11 days.
Some renowned watchmakers keep their distance from COSC as a testing institute and forgo certification of their products, even though these could easily meet the requirements. Overall, however, the testing procedure and its certificates enjoy broad acceptance. On top of that, certification fulfills an important marketing role in the interest of the Swiss watch industry. As a rule, a COSC-certified chronometer is a Swiss watch, since for several years now no watches have been certified whose movements are not cased by Swiss manufacturers.
Rolex Leads the Renowned Makers of COSC-Certified Wristwatches
Among the "regular customers" of the official Swiss chronometer testing institute are numerous illustrious names, with Rolex leading by a wide margin. In 2009, for example, the brand with the crown logo submitted more than 600,000 movements for certification – nearly half of all movements tested that year. Omega, Breitling, and TAG Heuer also have substantial numbers of their movements certified as chronometers. If you are looking for a chronometer-certified wristwatch, you will find a particularly wide selection at Rolex, in keeping with the large numbers it submits for testing.
From the Oyster Perpetual Explorer to dive watch classics such as the Submariner and GMT-Master to the Rolex Cosmograph Daytona, the majority of Rolex models available on the market bear the mark of a passed chronometer test on the dial.
Omega with Numerous Collections
Those who prefer to wear an Omega on their wrist can also choose from various models with an official chronometer certificate in the brand's lineup, for example in the Omega Speedmaster, Omega Seamaster Aqua Terra, or Omega Seamaster 300 M series.
Breitling, Tag Heuer, Chopard, Tissot
It almost goes without saying that brands such as Breitling and TAG Heuer, whose origins are closely tied to pilot's watches and motorsport respectively, also offer a range of certified precision timepieces.
The Breitling Navitimer 01, the Breitling Navitimer World, and the Breitling Superocean Héritage 42, for example, are available with the coveted certificate.
At TAG Heuer, the TAG Heuer Carrera Calibre 8 GMT and various models from the Grand Carrera series, for instance, have met the strict testing criteria.
Chopard's racing-inspired wristwatches likewise meet the chronometer standard, as several models from the Classic Racing Collection demonstrate.
By the way, a high-quality Swiss wristwatch with a chronometer certificate is not reserved for the upper luxury segment – you can get one for a three-digit euro sum. Prime examples are the Tissot T-Classic Le Locle Automatic COSC or, with a quartz movement, the T-Classic PR 100 Quartz COSC.
