The Timepiece Journal » watch buying guide

Ever received a chronometer certificate and wondered what all those numbers mean? This guide explains every field, every criterion, and what the data tells you about your watch movement.

Is a COSC chronometer certificate worth paying for? We break down what the certification actually tests, what it guarantees, and whether it matters for everyday wear.

Watch quality testing covers four stages: functional testing, performance testing (daily rate, isochronism, positional error, temperature coefficient), environmental testing, and power reserve testing. Here's what each test reveals.