Rolex watch repair service

What is the difference between a chronograph and a chronometer?

chronograph: From two Greek nouns; "chronos" meaning "time" and "graph" which means "write". A chronograph is a watch with hands that display hours, minutes and seconds, together with an additional mechanism enabling the user to measure continuous or intermittent periods from a fraction of a second to 12 hours.

chronometer: Also of Greek origin; "chronos" meaning "time" and "metron" which means "measurement". A chronometer is a precision time keeper regulated in different positions and at various temperatures which has passed a test of a recognized official body. The "COSC" (Controle Officiel Suisse des Chronometres) tests are performed in a laboratory over a 15-day period. They test the movement alone, using successive daily rate figures at different temperatures and with the movement in different positions.