ATM: Measures water resistance; Stands for "atmospheres" or the amount of pressure a watch can withstand before leaking; One atmosphere is equal to 10 meters of water pressure.
Bezel: Retaining ring topping the case and securing the crystal; Sometimes incorporates unidirectional or ratcheting movements, engraved or printed chapter markers, or complications such as a tachymeter.
Chronograph: Functioning similarly to a stopwatch, a chronograph is a unique and valued complication due to its ability to measure increments of elapsed time while the watch still maintains traditional timekeeping abilities. The crown controls the analog watch while function pushers allow you to start, stop and reset the chronograph subdials.
Chronometer: High-precision timepiece that has been tested and is certified to meet precision standards; Chronometer watches often come with certificates indicating their certified status.
Complication: Any feature added to the timepiece that does not indicate hours, minutes or seconds.
COSC Certified Chronometer: Refers to timepieces that have been christened with the title of chronometer. To become a chronometer, timepieces have to pass a test conducted by the Controle Officiel Suisse des Chronometers (COSC), roughly translating to Official Swiss Chronometer Testing Institute. COSC is a prestigious Swiss government agency that certifies the accuracy and precision of timepieces in Switzerland.
Crown: Part that allows you to manipulate the watch movement for a variety of purposes such as setting the hands, changing the date, winding the mainspring, etc.
Crystal: Transparent cover on a watch face that gives view of the dial.
Deployant: Type of clasp that keeps the closing mechanism hidden, creating an uninterrupted look for your bracelet or strap.
Exhibition Case Back: Unique complication wherein a crystal window is implemented into the back of a watch case, allowing view of the timepiece's movement.
Function Pushers: Manual controls on a case for when a movement features complications that require increased manipulation.
Greenwich Mean Time (GMT): Also referred to as Greenwich Meridian Time, the Greenwich Meridian Line is located at the Royal Observatory in Greenwich, England. It is the place from where all time zones are measured. Greenwich Mean Time is the average time that Earth takes to rotate from noon to noon. In this regard, GMT is thought of as "the world's time" and was once the basis with which every other zone set time.
Guilloche: Style of engraving that features wavy or straight lines, giving a unique effect when the timepiece is moved or shifted.
Ionic Plating: Process that produces a hardened surface that is durable and scratch-resistant; Has a black flat "stealth" finish.
Jewels: Within a movement, metal on metal contact creates wear and tear. Watchmakers use jewel bearings to reduce friction and help the delicate parts of the movement work smoothly and with great precision. Jewels help extend the movement's life. Diamonds, sapphires, rubies and garnets are the preferred materials. As a general rule, a higher number of jewels suggests a more prestigious movement.
Lugs: North and south ends of the case that attach to the strap or bracelet and often extend out from the dominant lines of the case.
Moon Phase: The lunar cycle has been a cornerstone of horology, the study of measuring time, since ancient days. Moon Phase is a complication on a timepiece that displays the various stages of the moon cycles from waxing to waning. It appears as a dial visible through an aperture which reveals the current moon phase.
Movement: Assembly making up the principal elements and mechanisms of a watch or clock; Includes the winding and setting mechanism, the mainspring, the train, the escapement and the regulating elements.
Power Reserve: Time a watch will continue running based on the movement's residual winding of its mainspring; In quartz and digital watches, this can also refer to the amount of energy left in the battery.
Push Button Dual Deployant: Similar to deployant and considered one of the most desirable and easy-to-use clasps, the push button dual deployant employs two small hidden push buttons that release the bracelet. This clasp keeps the closing mechanism hidden for an uninterrupted, seamless finish.
Retrograde: Hour, minute, second or calendar hand that moves across a scale and resets to zero at the end of its cycle.
Skeletonization: Reveals the intricate symphony of moving rotors, gears and springs which power a timepiece; The open design offers an insider's view, as unnecessary metal is cut away to allow the wearer to actually see the movement's skeleton.
Swiss Made: Since the 16th century, Switzerland has been the epicenter of watch making, producing some of the industry's greatest technological advances. The Swiss put a law into effect for all timepieces baring the words "Swiss Made": First, the movement must be assembled in Switzerland. Secondly, the movement must be cased up in Switzerland. Finally, the manufacturer must carry out the timepiece's final inspection in Switzerland.
Tachymeter: Scale on a watch used to determine units per hour, such as average speed over a fixed distance, or distance based on speed; Typically located along the outer rim of a dial.
Tritium: Self-powered illumination! Miniature tubes containing gaseous Tritium and layered with phosphor to power the luminous accents which can be seen for several meters in darkness.
Tritnite: Illumination requires no electrical power but must be "charged" by holding your watch close to any light source. The longer you hold it there, the longer and brighter you'll see the Tritnite.
Unidirectional Rotating Bezel: Used for tracking elapsed time. A ratchet mechanism prevents the bezel from rotating backwards. This feature is popular with divers, who rely on the elapsed time feature to prevent the diver from running out of air. The fact that the bezel cannot rotate backwards prevents the wearer from underestimating the elapsed time.About Stainless Steel:
Also called corrosion resistant steel, stainless steel is a steel alloy with added iron and chromium. The metal is rust-resistant, durable and highly lustrous. It has a similar appearance to platinum and polishes to a glistening sheen. Any scratches that may occur from day to day wear can be easily buffed away without endangering the piece. Please note, however, if the stainless steel is plated with another metal, the plating can wear off if rubbed excessively against hard surfaces.
Stainless steel was first recognized in France in 1821 by metallurgist Pierre Berthier. After several corrosion-resistance related discoveries and patents in Europe and the United States, Harry Brearley in England discovered a modern blend of stainless steel alloy. When it was announced by The New York Times in January of 1915, he was officially credited with the invention of this impressive modern metal.
Automatic: An automatic movement requires the same artful execution to create and contains virtually all of the same components as a mechanical movement - but with one notable addition. An automatic movement relies on the motion of the wearer's arm to spin an off-balanced weight called the rotor. A collection of gears inside the case utilizes the movement of the rotor to automatically wind the mainspring and power the watch. A slipping mechanism on the mainspring prevents the damaging effects of over-winding. Automatic watches require movement in order to function properly and will stop ticking after a period of dormancy when the reserve power in the mainspring is depleted. Timepieces with automatic movements are meant to be appreciated for the craftsmanship and complex aesthetic that they provide.
The case provides the foundation for all other major watch components. It houses the movement, maintains the lugs for attachment to the bracelet or strap, plays host to various crowns and function pushers, and seats the crystal and bezel.
Cases exist in a variety of shapes and sizes and utilize a library of materials for construction such as stainless steel, gold, ceramic, titanium, plastic, and more. The dominance of stainless steel in case construction remains, however, hypo-allergenic metals and materials, like titanium, continue to gain in popularity. Metal cases often have particular finishes - such as a smooth reflective polish or circular matte brush - that enhance the presentation of the timepiece and give it unique depth.
Some designs allow for the case and lugs to be curved in order for the watch to have a more comfortable fit around the wrist. The back of a case will typically be removable and most likely be screw down or pop-off. It is important to note, however, it should only be opened by a trained professional. An exhibition feature (found within a case's back) refers to an added window that allows you to view the movement and is often found on automatic and mechanical timepieces.
Case Size:
Case measurements do not include crown or lugs.
Watch Case Dimension Comparisons:
It can be difficult to determine how a watch will fit on your wrist without trying it on first. Get a better feel for the size of a watch case by comparing the case diameter to the following diameters of common objects:
