A mechanical movement that is wound through the movement of the wearer’s arm during normal daily arm motion; sufficient activity is necessary to build up a power reserve, also referred to as a “self-winding” watch.
The band is the part of the watch that secures the watch to the user. The two common terms used are Bracelet or Strap.
A metal link watch band, similar to a jewelry bracelet.
A ring that holds the watch crystal which may rotate and have special markings.
A highly polished or faceted gem stone such as a ruby or emerald used to accent the winding crown, lugs, and/or the dial hour markers.
The windows or sub-dials on the face of a watch that displays the day, date, month and/or year.
The outer body of the watch that contains the internal workings (the movement, dial and hands).
A watch that contains a stop watch feature: a timer that can be started, stopped, and/or paused to time an event or a series of events.
A watch movement certified to be accurate by the Contrôle Officiel Suisse des Chronomètres (Swiss Chronometer Control Board). Also see COSC.
The acronym for the Contrôle Officiel Suisse des Chronomètres (Swiss Chronometer Control Board), the official Swiss agency that certifies all watch movements that bear the internationally recognized and status of “Chronometer.” Also see Chronometer
The knob on the winding stem, often located at the 3 o’clock position, used to move the hands to set the time, as well as, to wind an automatic or manual movement.
The “glass” which protects the dial of the watch, often composed of a mineral glass, acrylic, or synthetic sapphire, is very hard to scratch, which is used on the majority of fine watches. A sapphire crystal is the most scratch-resistant and durable type of crystal.
Deployment Buckle or Clasp
A clasp mechanism that folds onto itself securing the two ends of the watch strap or bracelet. This type of fastener allows the wearer to slip on or remove the watch from their wrist with ease, and also provides a cleaner more finished appearance than the traditional buckle and tang closure.
This is the part that gives the watch its beauty, uniqueness, and character, also referred to as the watch face.
A watch specifically designed to withstand underwater pressure, 20ATM or greater, often worn by scuba divers. These watches are typically outfitted with a screw-down crown that creates a strong seal to prevent water from entering the case.
Dual Time/Second Time Zone Bezel
A rotating bezel which can be used to indicate the hour in an alternate time zone, different from the time designated by the hands on the dial.
A rubber or plastic ring used in order to seal the internal parts of the watch from the external environment. Typically used on in conjunction with the watch; crown, crystal, and case back.
A pattern made by interlacing engraved curved lines to create a decorative textural effect of the dial of the watch.
This is another name for a manual movement. Please see mechanical movement.
Elements used in watch movement as a bearing. Usually a form of synthetic ruby or sapphire, these are used for virtually frictionless pivots or hubs at certain critical places in the watch movement to minimize mechanical friction.
Extensions from either end of the case that hold the spring pin used to secure the strap or bracelet to the case.
Watch hands coated with a substance that makes them glow in the dark. They are especially common in sport model watches for better visibility underwater.
A type of mechanical movement, also known as a “hand-winding” movement, in which the mainspring of the movement must be wound daily by hand, using the crown.
See “mechanical movement“.
A movement powered by the use of a mainspring working in conjunction with a balance wheel. A mechanical movement may be:
automatic (self-winding) (wound by the motion of the arm during daily wear), or
manual (hand-winding) (requiring regular/daily winding of the crown by hand).
A special complication found on a few high end mechanical, and affordable quartz, watches that can announce the time in hours, quarter-hours, and minutes by means of a push button. An audible chime sounds when the push piece or button is depressed.
See also repeater.
A window, often half-moon shaped, in a watch dial that shows the current phase of the moon. This distinctive feature is usually seen in combination with other calendar-related features.
Mother-of-pearl (or nacre)
The iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. While mother-of-pearl generally has a milky white sheen, it is also exists in other natural pearlescent colors such as blue, grey, or pink.
A feature of a watch calendar that automatically adjusts to account for the different number of days in each month, and for leap years.
A measure of the amount of time a watch will function after being fully wound or powered, with no additional power input. Many modern mechanical watches have a power reserves that last 40 hours.
Power reserve indicator
A sub-dial on a mechanical watch that indicates how much longer the watch will operate before requiring additional power input. See Power Reserve.
A button that is pressed to operate a watch functions. Pushers are usually found on chronographs and timepieces with alarms.
Physical Vapor Deposit, a high-tech vacuum-coating procedure that produces a wear-resistant finish on the external parts of the watch, such as the case and bracelet.
An extremely accurate battery operated electronic movement utilizing the natural frequency of vibrations of a quartz crystal to regulate the operation of the timepiece.
A device that chimes the time when a pusher is activated or a slide is pulled.
See also Minute Repeater.
A crown that screws-down into the case tube thereby increasing the water resistant capabilities of the watch.
See “Automatic” above, which is the preferred terminology.
The ability of a watch no withstand a fall from a height of three feet onto a wood floor.
A watch band made of non-metal material such as: cloth, rubber, or leather.
Sweep seconds hand
A second hand that is mounted in the center of the watch dial, as opposed to mounted in a sub-dial. A sweep seconds hand is found only on mechanical watches, and has a motion that is unnoticeable to the human eye. On a quartz watch, the advance of the seconds hand is Discernible in tiny step-by-step jumps.
A tool used to compute speed based on travel time over a fixed distance travelled.
Thee tachymeter bezel or dial, is a logarithmic scale that simplifies the computation of speed of an object, by computing the following function:
Tachymeter Dial = 3600 / Elapsed Time In Seconds
*only able to measure speed greater than 60 miles per hour or 60 kilometers per hour
Also known as “tachometer”.
A rare and sophisticated complication, that compensates for the effect of gravity. found on only a select very high end mechanical watches. This feature eliminates the small variations in watch movement performance based on the position of the watch as a result of gravity.
The ability of a watch to withstand water pressure to a stated depth.
The internal element that transmits motion from the crown to the gears governing: movement, winding, and hand setting.