Over the years, we have learnt how important automatic watch movement accuracy is to our customers, whether they are someone who wears their watch every day or just on special occasions. No matter who you are, you need to be able to trust the accuracy of your mechanical timepiece and feel confident knowing it is telling you the correct time, over time.
But how do you know which automatic watch movement is the best? Well there is no simple answer to this question as all movements are different, but we do believe that one of the best ways to assure accuracy in a watch is to find one that is chronometer certified.
What is a chronometer certified watch?
A chronometer watch is a type of mechanical timepiece that has been monitored and tested to meet certain precision standards. They are monitored by the Contrôle Officiel Suisse des Chronomètres, otherwise known as COSC, and only movements which meet the precision criteria established under ISO 3159 are granted an official chronometer certificate.
For a watch to be considered COSC chronometer certified, it must go through several intense tests over 15 straight days, in 5 different positions and at 3 different temperatures. Some of the things tested are the average daily rate of seconds lost or gained, the mean variation in rates, the greatest variation, largest variation in rates, how much variation there is at different temperatures and rate resumption.
For a watch to be granted an official chronometer certificate it must have the following results:
- Average daily rate: +6 or -4 seconds per day
- Mean variation: 2 seconds per day
- Greatest variation: 5 seconds per day
- Difference of rates in vertical/horizontal position: +8 or -6 seconds per day
- Largest variations: 10 seconds per day
- Thermal variation: ±.6 of a second per degree Celsius
- Rate resumption: ±5
At C W Sellors, we always recommend chronometer certified watches for those that are in need of a highly accurate automatic watch. With COSC certification, you can feel assured it is one of the most reliable timepieces available.
We have a huge range of chronometer watches and COSC certified watches available on our website and in our stores. For more information on our luxury automatic watches for men and women, head over to our website or contact us on 01335 216004 or at sales@cwsellors.com.
