The terms chronograph and chronometer are often confused but actually refer to very different attributes of a watch. A chronograph is a watch (or other instrument) with two independent time systems, one indicates the time of day and the other measures short time intervals (ie a stop watch function) which allow the exact measurement or duration of an event. Chronographs can vary greatly in design and function with the stop-start counters relating to seconds, minutes and even hours thus the mini dials on the watch face. The term chronometer, for Swiss made watches, can only be given to a timepiece that fulfils certain strict criteria and meets a list of very high standards set by the Controle Officiel Suisse des Chronometres (COSC). In addition to this, a chronometer must be capable of permanently displaying the seconds. Clearly, a chronograph watch and a watch that has been certified as a chronometer are two different things. However, a chronograph can also be a chronometer if it has been certified by the COSC. A Swiss chronometer (with a certificate) is a timepiece of the highest quality. In order to achieve this certification a timepiece must undergo a series of precision tests in the most unfavourable temperature conditions and various positions (vertical, horizontal, side) and found to be within a certain time-keeping accuracy range. For watch movements to be given COSC chronometer status they must not lose more than 4 seconds or gain more than 6 seconds in a day. The COSC make particular note that their testing does not simulate how the watch movement will perform when it is on the wrist as such COSC tests are conducted on a watch movement when it is outside the watch case. Only about 3% of all Swiss watch production is given COSC certification. This is because many manufacturers either don’t submit their movements to COSC testing (as it is expensive) or do their own testing to superior standards (Germany’s Glashuette standard is higher than COSC). For example Sinn, Lehmann, Moritz-Grossmann, Hentschel, Dornblueth & Sohn, Habring2 and Armin Strom perform their own tests in-house on finished watches (ie watch movement within its case). In these cases the benchmarks are just as high if not higher in some cases.

The Tourbillon, an optional part for mechanical movements, is a rotating frame for the escapement, which is used to cancel out or reduce the effects of gravitational bias to the timekeeping. Due to the complexity of designing a Tourbillon, they are very expensive, and only found in “prestige” watches.