You may have seen some watches that are listed with something called a ‘COSC certification’. COSC stands for ‘Contrôle Officiel Suisse des Chronomètres’, which is the name of the organisation that awards this certification. Often we see this on more premium product ranges, as it is a prestigious certification for a model to receive. Today we will give you a short overview on what COSC certification is and why it is important.
What is COSC Certification?
As mentioned earlier, COSC-certified watches are awarded this title by a Swiss body called the Contrôle Officiel Suisse des Chronomètres. This translates to Official Swiss Chronometer Testing Institute in English.
The COSC is a non-profit organisation that operates to strengthen the prestige of the Swiss watchmaking industry.
The COSC Certification Process
To obtain COSC-certified status, watch manufacturers will send their products to the COSC. Here, it will undergo rigorous lab tests to ensure it meets the high standards of the qualification.
On day 0 of the testing, the movement of the watch will be placed in a five-slot clasp. Delivered unwound, the movement will then be wound according to its guidelines. Afterwards, its parts are put inside an enclosure which is kept to a heat of 23°C for roughly 12 hours. This is in order to stabilise the temperature for the actual testing.
For mechanical watches, this testing takes place daily for 15 days. But for quartz movements, testing is only daily for 13 days. Every day the movements will be wound and they will be assessed on their accuracy. According to the COSC website, the average rate should fall between -4 seconds to +6 seconds. That is to say, if a movement gains or loses too many seconds in a day, it will not be certified.
Judgement and Successful Candidates
In order to receive the certification, they are then judged on seven criteria. They must pass on each of the seven in order to be successful. These include the average daily rate, mean variation in rates, greatest variation in rates, difference between rates in horizontal and vertical positions, largest variation in rates, variation in rate depending on temperature, and rate resumption.
If successful, the watch model will receive the COSC certificate. Many brands chose to include a copy of the certificate in the packaging of the watch. However, these will have been slightly adapted in order to fit with the company’s visual branding. Moreover, brands may adapt the wording of this certification in their packaging. For example, COSC Rolex watches are described by the brand as ‘Superlative Chronometer Officially certified’. However, this still refers to the COSC certificate. Nevertheless, this is an indicator of a high-accuracy watch.
What Makes it Important?
The importance of the COSC certification lies in its respectability. By buying a watch with the certification, you can be assured that you are purchasing a high-accuracy timepiece that has undergone meticulous testing. In fact, the certification is so prestigious that in Switzerland, only models that have been certified by the COSC are allowed to call themselves ‘chronometers’.
Our COSC Certified Watch Recommendations
A budget-friendly piece: Certina DS-8 Chronometer Stainless Steel Bracelet Blue Dial C0334511104100 / C033.451.11.041.00
For a sleek yet simplistic COSC-certified watch, we would definitely recommend the Certina DS-8. The 316L stainless steel case, bezel and bracelet beautifully contrast the stunning Oxford blue sunray dial. Encasing this dial is an anti-reflective sapphire crystal for improved clarity and readability. Operating on a battery-powered, Precidrive™ quartz movement, this model boasts an accuracy of +/-10 seconds per year. Each Certina watch also has a Double Security feature, which both assures the longevity of the model and increases its shock resistance. The DS-8 is also water resistant up to 100 metres.
A multi-functional, midrange piece: Certina DS-8 Chronograph Moonphase Brown Dial C0334601608700 / C033.460.16.087.00
The next contender on the list is also a Certina model, but this time the DS-8 Chronograph Moonphase. The dial is a smooth brown colour, paired with rose-gold indices and a brown leather strap. Benefitting from the same anti-reflective sapphire crystal, Precidrive™ quartz movement and Double Security feature as above, the DS-8 Chronograph also has several other useful functions. The dial features a Moonphase window, chronograph, a date window at the 4 o’clock positioning, as well as Super-LumiNova hands. The vintage military feel of this piece also makes it a visually intriguing timepiece at a great midrange price.
A classic and limited edition piece: Ball Watch Company Trainmaster Endeavour Chronometer Limited Edition Leather NM3288D-LL2CJ-WH
A classic antique design, the Ball Watch Company’s Trainmaster Endeavour oozes splendour. Designed to commemorate Captain James Hook’s first voyage aboard the HMS Endeavour, only 250 pieces of this model exist. In fact, on the case back you can find a beautiful engraving of Captain James Cook himself. For maximum readability, the dial features distinctive blue hands. This is truly a remarkable and unique model, but its value surpasses the purely superficial. With a minimum magnetic resistance of 4800 A/m and a shock resistance of at least up to 5000 Gs, this watch is incredibly robust. Moreover, the premium stainless steel that comprises the case and lugs is low carbon. Such a unique model is bound to make you stand out from the crowd.
A heritage luxury piece: LONGINES SPIRIT ZULU TIME GMT 42mm Black Dial Green Bezel L38124632 / L3.812.4.63.2
Many Longines lines have a COSC certification, but the Spirit collection might just be our favourite. A best-selling model, the Longines Spirit celebrates legendary military pioneers, combining heritage with contemporary technical excellence. Its standout features include a forest green ceramic bi-directional rotating bezel and a scratch-resistant sapphire crystal finished with several layers of anti-reflective coating. The Spirit also excels mechanically and has an automatic movement with a 72-hour power reserve, beating at 25’200 vibrations per hour.
A top-of-the-range piece: Baume & Mercier Clifton Baumatic 40mm Black Dial Black Alligator Strap M0A10692
Beautifully crafted, the Baume & Mercier Clifton Baumatic is our final and most luxurious contender on the list. Attention to detail is paramount on the Clifton, with riveted trapezoid rhodium-plated indices and alpha-shaped hands. The dial itself is pristine and clear and is divided by a fine white line design. There is also a magnified date display at 3 o’clock. Enclosed in the display case back is a Swiss-made automatic movement that has a power reserve of 120 hours. From front to back, this is a stunning model that is definitely worth the investment.
In conclusion, the COSC certification is great for giving you that extra layer of quality reassurance when buying a timepiece. It ensures that the model has been well-tested for its reliability and durability.
We hope that our recommendations help you in your search for your perfect COSC model, but we also have many more men’s and women’s options available on our website too. Do you have any COSC watch recommendations? Let us know in the comments down below!
