Precision and reliability are two essential characteristics for lovers of mechanical watches. One way to ensure these attributes is to obtain a chronometer certification issued by the Swiss Official Chronometer Testing Institute (COSC). Find out in this article everything you need to know about this prestigious certification.

What is the COSC certification?

THE Official Swiss Chronometer Testing Institute (COSC) is an independent organization that certifies the precision and reliability of watch movements by carrying out rigorous tests. Founded in 1973, its mission is to assure consumers that watches bearing its certification meet strict standards for performance and quality.

Certification criteria

A watch movement submitted to the COSC must meet several criteria before being certified as a chronometer. Among these requirements are:

• A minimum precision of -4/+6 seconds per day for mechanical watches, and ±0.07 seconds per day for quartz watches
• A minimum power reserve of 38 hours for the mechanical movements
• Impact resistance according to ISO 1413
• Magnetic resistance in accordance with ISO 764

These criteria ensure that COSC-certified watches are not only accurate, but also reliable and durable.

The certification process

To obtain COSC certification, a watch movement must undergo a series of rigorous and intensive tests. The process usually takes several weeks and takes place in three main stages:

1. Registration: the manufacturer submits its movement to the COSC for evaluation. It must provide detailed information on the technical characteristics of the movement as well as on the production conditions.
2. The tests : the movement is subjected to a battery of tests to verify its precision, reliability and resistance. These tests include performance measurements in different positions, temperatures and environmental conditions.
3. The certification : if the movement successfully passes all the tests, it is certified as a chronometer and receives an official certificate attesting to its performance. This document contains detailed information on the results obtained during the tests.

The benefits of COSC certification

Obtaining COSC certification has several advantages for watch manufacturers and consumers:

• A guarantee of quality : the certification attests that the movement has been rigorously tested and meets high standards for precision, reliability and performance. This reinforces the manufacturer's reputation and reassures consumers about the quality of their watch.
• A competitive advantage: a COSC-certified watch differentiates itself from other models on the market and can therefore sell for a higher price. This distinction is particularly important in the high-end sector, where consumers are looking for exceptional products.
• Added value for collectors: COSC-certified watches are often sought after by watch collectors, who appreciate their precision and rarity. These models can therefore increase in value over time and constitute an interesting investment.

Flagship brands and models of COSC-certified watches

Many well-known watch brands are proud to offer COSC-certified watches to their customers. Among the most famous are:

• Rolex: the Swiss brand is arguably the most iconic when it comes to COSC-certified watches. All its models are subject to official control and proudly display this distinction.
• Omega: the other Swiss giant is also a strong supporter of COSC certification. Its Speedmaster and Seamaster watches are notably certified as chronometers.
• Breitling: this brand specializing in measuring instruments for aviators is known worldwide for its COSC-certified watches. Collectors particularly appreciate the Navitimer and Chronomat models.
• Tag Heuer: the Swiss watchmaker, official partner of several F1 teams, also offers COSC-certified watches, particularly in its Carrera range.

The Swiss Official Chronometer certification (COSC) is a guarantee of quality and precision for mechanical watches. It allows manufacturers to differentiate themselves on the market and offers consumers the assurance of acquiring an exceptional product.