Annual Calendar | Automatically adjusts for months with different lengths i.e. 30 days, 31 days etc. Also normally features indicators for date, day of week, month and often moon phase. Does NOT make allowances for leap year and the 4 year cycle like a Perpetual Calendar. |
Chronograph | A stopwatch function, normally with dials indicating elapsed seconds, minutes and hours for the specific event being measured. |
Chronometer | Technically means an instrument which measures time (a watch). Swiss watches described using this term usually mean the watch is COSC tested and approved for accuracy by the government approved, Controle Officiel Suisse de Chronometrage. |
Ebauche | An industry term for a base mechanical watch movement before any modification. |
Exposition or skeleton | These terms can be used to describe the dial or case back of a watch and indicate that some or all of the movement is visible through the sapphire crystal. |
GMT (second timezone) | Greenwich Mean Time denotes that the watch has a second time zone indicator. |
Guilloche | Refers to the special texturing or machining of a surface on a watch, most commonly on the dial, generally a detail found on finer timepieces. |
Mechanical Movement | Used to described a watch movement that doesn’t require a battery (i.e. a quartz watch). A watch with this movement could be wound daily or in the case of an automatic movement (also considered mechanical), it is simply powered by the movement of the wearer’s wrist. |
Minute Repeater | Considered one of the most complicated mechanisms whereby hammers and gongs signal the hours, quarter hours and minutes acoustically. The most complicated of these minute repeaters have 3 gongs (carillon), most have 2. |
Perpetual Calendar | Automatically adjusts for months with different lengths, i.e. 30 days, 31 or 29 days. Also features indicators for date, day of week, month and moon phase automatically adjusting for leap year. |
Power Reserve | Denotes the amount of power a mechanical watch has when fully wound. Many models feature an indicator that displays the remaining power, often called the reserve de marche. |
Quartz Movement | A battery operated movement which uses the vibration frequency of a quartz crystal to regulate the operation of the watch. |
Ratrappante (split chronograph) | A watch featuring a double chronograph, 2 separate stopwatch mechanisms for the purposes of measuring 2 separate events simultaneously. |
Tourbillion | Considered a very special complication in a mechanical watch. A Tourbillon mechanism compensates for the effects of gravity on the balance thus improving the overall accuracy of the watch. Originally invented by Abraham Louis Breguet, the watch’s escapement (balance, lever and escape wheel combined) is housed in a cage which rotates every 60 seconds |