What is the difference between a Chronometer and a Chronograph?
The term chronometer is registered. Only a watch, whose movement was tested by an officially recognized testing laboratory and met the performance criteria, may use the term chronometer on it. In Germany, the testing laboratory is in Glashütte (see www.imet.de). In Switzerland it is the Controlé official Suisse des chronometers, or abbreviated C.O.S.C. (see www.cosc.ch).
This is a very common question since people often confuse the two. While their names may sound similar, these terms have very little in common. Chronometer is the term used to describe a highly-precise timepiece which, after rigorous testing, has received an official timing certificate from the official Swiss timing bureau Controle Officiel Suisse des Chronometres (COSC). Thus, it is a rating or accolade given for the watch’s accuracy. A chronograph on the other hand is a timepiece that, in addition to the normal time telling functions, also performs a seperate time measuring function such as a stop watch — with a seperate seconds hand which can be started, stopped and reset to zero, via push-buttons on the side of the case. Please do not confuse ‘chronographs’ with ‘complications’ (which are described below). While all chronographs can be considered complications, not all complications are in fact chronographs.
