Rolex, like other Swiss watchmakers, relied on "Bureaux Suisses - de Controle Officiel de la Marche des Chronometres (Swiss Institute for Official Chronometer Tests)"  to certify that Rolex movements met or exceeded the standards required to be designated "official chronometers."

The institute is an independent testing organization that certifies watches to this day. Rolex watch movements were tested for accuracy in varying positions and temperatures. In the earlier years, their results were logged by hand or typewritten on the larger timing certificates. Afterwards, the movements were sent back to Rolex with the certificates.

Swiss watchmakers used this independent testing organization to help them establish a strong reputation for manufacturing quality timing instruments. Sales and marketing literature touted the watches with movements as "Officially Certified Chronometers." 



In addition to the timing papers issued by Bureaux Suisses, Rolex produced a small "Chronometer certificate" card that designated the watches that accompanied it as an "Officially Certified Chronometer."

Rolex also printed "Officially Certified Chronometer" and "Superlative Chronometer Officially Certified" directly on the dial of models that passed such testing. Of course, there was additional cost for this certification and a premium price was charged for watches that went through this process.

Models such as the 5513 and the earlier Daytona models such as 6234/ 6238/6239/6241/6240 were not certified chronometers. Rolex did certifications for the gold version of the Daytona 6263/6265 models much earlier than the steel models. Presumably the steel 6263/6265 received chronometer certifications for their movements late in their production cycle, although their dials never reflected the chronometer rating. But the paperwork accompanying some of these later 6263/6265 steel watches were chronometer papers with the words "Attestation de Chronometre Officiel."

Rolex began to phase out using the Bureaux Suisse certificates in the late 1960s probably due to the volume of watches that had to be certified. The Bureaux Suisse allowed the use of its red seal on batches of tested movements and Rolex started producing its own green paper certificates titled "Attestation de Chronometre Officiel"  with the Bureaux Suisse seal at the bottom left corner. The latest Bureaux Suisse certificate I have is dated October of 1968 with a watch serial number of 1.87M.



From the earliest papers until about 1970, guarantee papers and chronometer certification papers were two separate papers, as described above.

Chronometer papers were meant to 'prove' to the purchaser that a watch had passed a set of standardized tests that qualified the watch to be designated with a chronometer rating.

Guarantee papers were meant to warranty the watch to be free from defects for a period of 1 year from the date of sale. (Sometime in the 1980s that was extended to 2 years). Some Guarantee papers also had "Rolex Superlative Chronometer" on the front cover.

Circa 1970, or a just prior to the 3,000,000 case number, Rolex combined the one year warranty ("Garantie") with the chronometer certification ("Attestation de Chronometre Officiel"). All Rolex papers to this day have the guarantee and chronometer certification combined.

Watches that were not chronometer rated, such as the Daytona models, continued to be accompanied by a smaller green "Garantie" paper that did not have the chronometer certification "Attestation de Chronometre Officiel" or the red seal in the bottom left corner.