Is Rolex precision -1/+5 (better than COSC)?

[delldeaton]

Just read on Sheldon's site (www.minus4plus6.com) that Rolex watches perform to a standard of -1 to +5 seconds per day, which is why each is called a "Superlative Chronometer."

• COSC spec is -4/+6
• Omega claims -1/+6

Is this information regarding Rolex watches correct?

Can anyone point me to an original source for this?

Thanks!

[SPACE-DWELLER]

Maybe this article called "Inside COSC" sheds some light on the matter.

Official COSC specs are minus 4 to plus 6 seconds. But some companies have their own "official" COSC specs, for instance Omega (as you state), giving you information about how the company in question would test the movements by themselves after getting them back from COSC testing.

Interesting note in the article, btw. I qoute:

"According to Rolex, the rejects are fixed and sent back to COSC until they pass. "We don’t use COSC to tell us how good our movements are," said a source deep inside the Wilsdorf foundation. "We test them ourselves. All we want is the chronometer certification. It’s for marketing."