Rolex Superlative Chronometer Certification

All Rolex movements receive certification from the Swiss Official Chronometer Testing Institute (or COSC) before going into their respective cases. This certifies that those movements are precise within up to -4/+6 seconds a day. After the watches are assembled, they receive an in-house certification by Rolex known as the Superlative Chronometer Certification that certifies their precision up to -2/+2 seconds per day. 

Rolex Superlative Chronometer Green Seal (photo: Rolex)

The green seal shown above comes with all new Rolex wristwatches based on this certification. They also have the words 'Superlative Chronometer' inscribed on their dials. The certification consists of testing precision, waterproofness, power reserve and self-winding.

The precision of each fully assembled watch is tested over a 24 hour cycle. Waterproofness is tested by submerging each watch into a hyperbaric tank. The water pressure in the tank is set to the equivalent of 10% over the depth rating for most models, 25% for dive watches.

All of these extra steps are taken by the watchmaker to guarantee that all of their watches meet their own standards of quality and excellence in Swiss watchmaking.

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