Quote:
Originally Posted by Bfd70
... the Contrôle Officiel Suisse des Chronomtres (COSC) standard deviation rate of -4 to +6 seconds within a 24 hour day, tested over a ten day period of chronometer testing, in five positions and at three temperatures. Watches that are within -4 to +6 seconds deviation in a 24 hour period are awarded Official Chronometer Certification by COSC and the movement is engraved with a chronometer serial number. Rolex has a self-imposed stricter standard of -1 to +5 seconds per day and hence the designation, "Superlative Chronometer Officially Certified" on the dial of any certified Rolex watch
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That's just a internet myth about the -1+5 second standard,and don't read too much in the the wording "Superlative" in front of the official designation of Chronometer.As today its merely a Rolex marketing ploy to give it a more distinguished sound to the chronometer status of their products. Any words added before or after the official designation of Chronometer are merely purely marketing,likewise the wording Certified Chronometer,is a redundant phrase word, since getting the Chronometer status is the certification,but the certification is only at the time of testing the bare un-cased movement.And all Swiss chronometers of the same size as Rolex movements are tested to exactly the same standard as any other certified movement of the same size as Rolex.And today most mechanical movements made with some very careful regulation could meet or pass the COSC spec today.