What does a COSC certification or Chronometer rating on a watch really mean to me?


The value of a COSC certification or Chronometer rating is just like beauty: the value is determined by the eye of the beholder. For premium brand companies like Rolex and Omega its clearly used as a kind of marketing tool to promote the fact that there brand is special and unique. And that when you spend a lot of money on their products you’re getting a product that simply can’t be matched by those other less certified makers of mostly mechanical watches.

Detractors point out, however, that the certification process has flaws and is in fact not a very beautiful lady. Their complaints state that there are flaws in the certification testing process, that other testing bodies offer more stringent and contemporary testing, and that these particular ratings are more marketing tools than honest assessment of what quality of wristwatch you’re actually getting. But first let’s address the question of what exactly is the COSC.

What is the COSC?

The acronym COSC stands for “Controle Officiel Suisse des Chronometres, which translates to mean the “Official Swiss Chronometer Testing Institute”. This current incarnation of this type of testing facility, which has a history dating back more than a hundred years, was conceived back in 1973 and is run as a Swiss nonprofit, according to the organization’s website. The organization, again according to its websites, has labs in Bern, Geneva, Neuhatel, Solothurm and Vaudi. Each lab is organized independently from the others.

What are the methods of a COSC Certification?

Now while there is some dispute as to how meaningful a COSC Certification is there should be no dispute that the measurements are detailed and thorough even though they don’t involve the entire watch and apparently companies are allowed to “juice” the watches they send for testing.

The watch components themselves — its clear that this isn’t the entirety of a watch or even the whole completed watch — are tested over a 16 day period where the mechanics of the watch are stress tested in a variety of ways and are measured against the accuracy of at least two in house atomic clocks.

The COSC tests more than a million watches a year. The testers of the COSC also offer an answer to how valuable their testing services are. They make the claim, on their website, that non certified watches can’t match certified chronometers because the quality of parts has to be higher than average and in fact requires a significant investment on the part of say a Rolex or an Omega brand. But there are some dissenting views.

The Various Cons of COSC Testing

First, you have to keep in mind that the COSC isn’t the only measuring authority for mostly mechanical watches. Japan has one called the “Grand Seiko”. The Germans have a testing site known as the Glashutte Observatory. There is even a test called the “1000 Hours Control, which seems to originate from France, and claims to have created a more rigorous and objectively fairer test for wristwatch quality, according to its possibly biased and self serving website.

Second, as the late proprietor of a very popular website about watches phrased it, you can get 20 dollar watches that are as accurate or more accurate than thousand dollar watches. He makes the point that when you pay big money for certified chronometers you’re not paying for test results but you’re making more of an artistic and aesthetic determination. Not to mention that the resale value of a Rolex is probably better than a Kmart special. You’re not looking at a score but how that product makes you feel.

So, bottom line, these certifications should be taken with a grain of salt. No doubt they measure something valuable but the test doesn’t measure the entirety of value, either objectively or subjectively.

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