COSC is, basically, -4/+6 as Stonehenge said. There are no other widely accepted independent certifications of a chronometer as far as I’m aware. Omega’s METAS “master chronometer” certification is their own definition (adding magnetic resistance), as is Rolex’s “superlative chronometer” standard of -2/+2.
COSC is, basically, -4/+6 as Stonehenge said. There are no other widely accepted independent certifications of a chronometer as far as I’m aware. Omega’s METAS “master chronometer” certification is their own definition (adding magnetic resistance), as is Rolex’s “superlative chronometer” standard of -2/+2.