One of the criteria for « chronometer » certification is the average daily rate on the first 10 days of testing: from -4 sec to +6 sec., or up to 10 seconds per day. A tolerance which, as such, may appear high, but which, in reality, is the result of an extraordinary requirement.
Even if a watch gained 6 seconds every day, it would mean not only that it was remarkably regular, but also that the error made after one year would be equivalent, using the metric system for comparison, about 7cm for every 1000m! But a mechanical watch fluctuates slightly depending on the temperature and its position, partially compensating for its own deviations – which is the prime mark of a high quality mechanical watch.
The technical value of a certified chronometer compared to a model that does not carry the certification is incalculable.
Because it also represents the recognition for the brand of a flawless quality system – the proof that the notion "chronometer" has informed its every level of production: research and development, design, production, choice of components and of partners, assembly, adjustment, control, with a constant concern for the criteria that define a true chronometer. The failure rate among major brands is extremely low compared to the volume submitted, which is proof of the rigour of the brands in question.
The chronometer certificate is not obtained by chance: It is the symbol of a culture of high quality manufacturing, precision, and exacting standards – in a word, of the passion that drives Swiss watchmakers.