Perfect Timing
Among other key attributes, a fine watch is inevitably judged by its ability to keep precise time. We look at the various ways in which a timepiece can earn chronometer certification, the accepted industry nd standard for exceptional accuracy
What it takes to earn chronometer certification, the accepted industry standard for accuracy
Awatch may have a fancy tourbillon, multiple layers of lacquer on its dial and a strap of the most supple calfskin, but what use is it if it doesn’t keep good time? Because no matter the brand, the style or the price, it’s the steadfast pursuit of precision timekeeping that lies at the heart of watchmaking. For a watch to be considered exceptionally accurate, it must carry chronometer certification. As there are several ways in which certification can be achieved, however, with some watchmakers arguing that their standards – as well as internal and external tests – are loftier and more rigorous than others, that isn’t quite as simple as it sounds.
As far as European watchmaking is concerned there are four generally accepted standards for accuracy certification, all of which – not surprisingly – have been set by the Swiss watch industry.
CHRONOMETER CERTIFICATION The Swiss watchmaking industry’s independent testing institute – the
Contrôle Officiel Suisse des Chronomètres ( COSC) – subjects every movement submitted for testing to a rigorous process defined by the ISO 3159 standard, which is the baseline for establishing mechanical chronometric accuracy. Each calibre undergoes a 15- day testing regimen, during which it’s kept in various positions and at a range of stipulated temperatures, remaining in each position and temperature for 24 hours. After each test it’s briefly removed from the thermal enclosure for measuring with a vision machine equipped with five cameras. The final results meet seven criteria: average daily rate of accuracy, mean variation in rates, greatest variation in rates, the difference between rates in horizontal and vertical positions, largest variation in rates, variation in rate depending on temperature, and rate resumption. Only by meeting the set numbers can a movement receive chronometer certification. One criterion for a chronometer is that it keeps time within a minus- 4/ plus- 6 seconds- per- day variation, though as this is a minimum requirement, accuracy in real terms is often better than the requirement. Watch brands are naturally keen to boast that their movement has passed the COSC examinations by prominently displaying the word “chronometer” on the dial.
FLEURIER QUALITY FOUNDATION
The Fleurier Quality Foundation ( FQF) promotes itself as the first qualitative horological certification for finished watches that are manufactured
100 percent in Switzerland. Coestablished by a number of brands in the small watchmaking community of Fleurier in Switzerland’s Val- de- Travers, the foundation includes names such as Parmigiani Fleurier and Chopard, and has a statute that regulates its transparency and independence. Unlike COSC, the FQF’S jurisdiction has been expanded to encompass quality of finishing, manufacturing origin, chronometry ( certified first by COSC), durability ( the Chronofiable test) and real- life wear simulation ( the Fleuritest simulator). Before submission, a movement has to be COSC certified; it’s then put through a second level of FQF testing. The Chronofiable test, for example, measures pull- and- push forces on the stem, the forces exerted on the push buttons ( such as chronograph controls and correctors) and the turning bezel, and magnetic, water and shock resistance, while the Fleuritest simulator mimics the movements of a nychthemeral cycle, alternating between active and placid, in a 24- hour test within the machine. When accuracy is measured to within 0/ plus- 5 seconds per day, the FQF emblem can be engraved on the movement.
MASTER CHRONOMETER
For a movement to be awarded Master Chronometer certification in a series of tests jointly introduced by Omega and the Swiss government’s Federal Office of Metrology ( Metas) in 2015, it must first receive COSC certification. It’s then subjected to a further eight tests over a 10- day period, the first determining the movement’s resistance to magnetism from, say, loudspeakers or metal detectors, by exposing it to a magnetic field of 15,000 gauss. On completion, a second test “tortures” the watch head; this is followed by further tests involving magnetisation and demagnetisation at a range of temperatures and positions over a four- day period. Accuracy is calculated using daily records of the watch’s precision measured against an atomic clock, and must fall within a range of 0/ plus- 5 seconds per day – or a maximum deviation of 0.0058 percent over a
24- hour period ( which is half that required by COSC). For the fifth test, the watch is placed in six different positions and changed every 60 seconds, while the sixth test requires the watch be placed in six different positions with power reserves of 100 and 33 percent. The seventh test measures the power reserve’s longevity, with the final test ascertaining the accuracy of the advertised water resistance. Once a watch meets all the above requirements it qualifies for Master Chronometer certification ( meaning that every Omega Co- Axial Master Chronometer movement has survived the test and is functioning as intended).
PATEK PHILIPPE SEAL
The Patek Philippe Seal, which celebrated its 10th anniversary this year and can be found on the bridge of a Patek movement, is the maison’s own replacement for the Poinçon de Genève ( Geneva seal). Unlike the latter, which primarily encompasses aesthetics and craftsmanship, the Patek Philippe Seal applies to all aspects of a watch – including manufacturing, accuracy and lifelong maintenance – and is overseen by an independent supervisory board. Besides a minus- 3/ plus- 2 seconds- perday accuracy range for a movement larger than 20mm in diameter, there’s an exhaustive list of further requirements. The movement, case ( both inside and out), dial, push pieces and crowns must be perfectly made and immaculately finished – diamonds, for example, must be of flawless Top Wesselton grade. Depending on its complexity, precision tests on an uncased movement may last as long as one month, while those on a finished watch, which include a kinetic simulator, can take another 20 days. Tolerances for a tourbillon watch are tighter, with accuracy in the range of minus- 2/ plus- 1 seconds daily and the greatest permitted deviation in all six measuring positions not exceeding 4 seconds a day. Water resistance is tested in air with overpressure as well as underwater at pressures ranging from 3 to 12 bar, depending on the model, with a following condensation test. Before delivery to the retailer in a vacuum seal, the watch is visually inspected for flawless appearance one last time.