3 articles with this tag
A chronometer is not a chronograph. A working dealer's plain-English guide to chronometer certification: what COSC actually tests, the -4/+6 standard, how Rolex Superlative and Omega Master Chronometer go further, and the stricter Excellence Chronometer tier COSC introduced in February 2026.
Grand Seiko just built a mechanical watch that drifts only 20 seconds a year, the latest shot in a quiet arms race over accuracy. A working dealer's read on how the chronometer ladder actually works, from COSC and Rolex's -2/+2 to Omega's Master Chronometer and Spring Drive, why for a watch you actually wear the differences are mostly bragging rights, and where the real value still sits.
Rolex strengthened its Superlative Chronometer certification in 2026, adding three new criteria at the design and manufacturing stage. A working dealer's read on what the green seal and the five-year guarantee actually mean when you are buying pre-owned, and why the upgrade changes almost nothing about an older watch.