A common material used for watch crystals (which cover and protect the watch face), acrylic is an inexpensive alternative to mineral or sapphire crystals. Though less durable and more susceptible to scratching than mineral glass or sapphire, acrylic is not easily shattered and can be polished to remove scratches. See also Mineral Crystal and Sapphire Crystal.
The Standard Atmosphere is a unit of pressure equal to 101,325 Pa, 1.01 bar or 14.7 psi.
When applied to water depth, 1 atm is equal to the pressure exerted by the weight of a column of freshwater approximately 10.3 meters (33.8 feet) deep/tall. Thus, in terms of water resistance ratings for watches, a watch at a depth of 10.3 meters experiences a pressure of 1 atm, and a water resistance rating of 30 atm is equivalent to a depth of 300 meters. In the world of dive watches, 1 atm is equivalent to 1 bar which is equivalent to 10 meters of water depth. See also Bar.
An automatic movement (sometimes referred to as 'self-winding', 'automatic mechanical' or simply 'auto') is powered by a mainspring, but does not require manual winding. Instead, the motion of the wearer's arm and wrist activates an internal oscillating rotor, which in turn winds the mainspring. When fully wound, some automatic movements have a power reserve of up to 50 hours (meaning they can run for up to 50 hours with no additional winding).
The bar is a metric unit of pressure equal to 100,000 Pa, 0.987 atm or 14.5 psi. When applied to water depth, 1 bar is equal to the pressure exerted by the weight of a column of freshwater approximately 10.3 meters (33.8 feet) deep/tall. Thus, in terms of water resistance ratings for watches, a watch at a depth of 10.3 meters experiences a pressure of 1 bar, and a water resistance rating of 30 bar is equivalent to a depth of 300 meters. In the world of dive watches, 1 bar is equivalent to 1 atm which is equivalent to 10 meters of water depth. See also Atmosphere (atm).
An external ring which encircles the crystal. On sport, pilot and dive watches, the bezel often includes calibrated markings and may rotate in one or both directions. Bezels on dive watches typically feature minute markings for measuring elapsed time and usually rotate only in a counterclockwise direction as a safety precaution. This way, if the bezel is inadvertently moved after being set, the indicated elapsed time will never be less than the actual elapsed time.
The housing which contains the movement and internal parts of a watch. The most common material for metal cases is stainless steel. Other common case materials include resin (plastic), titanium, brass and gold.
The back side of the watch, which contacts the wearer's wrist and is typically removable to allow access to the movement. Usually pressed or threaded into the watch case and often engraved or otherwise marked with details about the case material, movement, model number, etc. Some casebacks are transparent (mineral glass or sapphire) to provide a view of the movement inside.
A ring which sits between the dial and crystal and encircles the watch dial. Often made of metal or plastic, the chapter ring is sometimes printed with markings, such as minute indices.
An additional mechanism or feature in a watch movement beyond the basic function of timekeeping. Common complications include day/date calendars, chronographs and moon phase mechanisms.
The knob or button on the exterior of the watch case used to set the time and date (if the watch includes a date feature). In mechanical watches, the crown is also used to wind the mainspring.
Some watches, particularly those with higher water resistance ratings, include a screw-down crown which threads onto the stem tube.
Sometimes referred to as the "glass", this is the part of the watch which covers and protects the watch face/dial. Common watch crystal materials include acrylic, mineral glass and synthetic sapphire. See also Acrylic, Mineral Crystal and Sapphire Crystal.
The face of a watch, which typically includes numerals or other markings to indicate hours, minutes and seconds. Some dials include a date window for viewing the calendar and smaller subsidiary dials referred to as sub dials or eyes.
Synthetic rubies or sapphires that function as low friction bearings for the gears inside a mechanical watch movement.
Projections on opposite sides of the watch case to which the watch strap or bracelet is attached.
The distance between the case lugs. Commonly expressed in millimeters (e.g. 20 mm, 22 mm), this distance determines the width of the strap or bracelet that will fit the watch.
Self-illuminating paint used on the hands, dial and bezel of a watch. Sometimes referred to as photo-luminescent, radio-luminescent, luminous or phosphorescent. After exposure to light, luminescent hands and markings glow to provide better visibility in low light conditions.
Luminescent pigments are characterized by their body color, light emission color (blue or green) and afterglow color (a combination of body color and light emission color).
The mainsprings is a long, elastic, spirally wound strip of steel which provides the power supply for mechanical movements.
A mechanical movement is powered by a mainspring which slowly unwinds and requires regular winding to continue running. When fully wound, some mechanical movements have a power reserve of up to 50 hours (meaning they can run for up to 50 hours with no additional winding).
A commonly used material for watch crystals (which cover and protect the watch face), mineral crystal (or mineral glass) is a form of hardened glass which is more scratch resistant than acrylic, but less so than sapphire. Though more easily scratched than sapphire, mineral crystals are less prone to shattering on impact. See also Acrylic and Sapphire Crystal.
The mechanism or "motor" in a watch which is responsible for keeping time, moving the watch hands and performing other functions the watch may include. The two most common types of movements are quartz and mechanical (including automatic mechanical).
PVD (PHYSICAL VAPOR DEPOSITION)
A type of vacuum deposition used to deposit thin films of material on various surfaces. The coating method involves a physical process---such as high temperature vacuum evaporation with subsequent condensation---rather than a chemical reaction as in chemical vapor deposition.
The length of time a mechanical watch will run from fully wound to stopped, without additional winding (or in the case of automatic mechanical watches, without additional movement).
Describes a watch movement regulated by a synthetic quartz crystal which draws power from a small battery and oscillates at 32,768 Hz (32,768 times per second). An electronic circuit divides this oscillation into precise increments of 1 second. Though it may be argued that quartz movements are less elegant than their mechanical counterparts, they are generally more accurate and durable.
See Power Reserve.
The oscillating weight inside an automatic mechanical movement which winds the movement's mainspring. The rotor in turn is powered by the motion of the wearer's arm and wrist.
A secondary clasp that closes on top of the main folding clasp on a watch bracelet to prevent the main clasp from opening accidentally.
A commonly used material for watch crystals (which cover and protect the watch face), sapphire crystals are made from synthetic sapphire, which is formed by crystallizing corundum (aluminum oxide) at extremely high temperatures. Once molded into discs, the material is then machined to the right size and thickness and polished. Extremely hard (with a rating of 9 on the Mohs Scale), sapphire crystals are highly scratch resistant, but more susceptible to shattering than mineral or acrylic crystals. See also Acrylic and Mineral Crystal.
SCREW-DOWN / SCREW-IN CROWN
A crown which threads onto the stem tube. Often found on watches with higher water resistance ratings.
Spring loaded bars or pins used to attach the watch strap or bracelet to the watch case and attach buckles and clasps to straps and bracelets.
Super-LumiNova is a registered trademark of LumiNova AG Switzerland, a joint-venture between Nemoto & Co. Ltd. of Japan and RC TRITEC Ltd. of Switzerland. A leader in the field of luminescence, RC TRITEC produces luminescent pigments used by watch manufacturers worldwide, and their Super-LumiNova pigments are widely recognized as the best and brightest available. For more information about the company and their products, please visit their website.