WATCHMAKING GLOSSARY
Amplitude
The maximum angle by which a balance or pendulum swings from its rest position. Each swing in either direction is called a “beat”. Amplitude is the number of degrees of rotation of the beat. Amplitude is higher, typically in the range of about 270 to 315 degrees, when a watch is lying flat or in the “dial up” or “dial down” position. Amplitude usually falls when the watch is in a vertical position, primarily due to increased friction.
Analog or Analogue
A watch displaying time indications by means of hands.
Analog Quartz
The most commonly-used term in referring to any analog timepiece that operates on a battery or on solar power and is regulated by a quartz crystal.
Annual Calendar
A watch that automatically adjusts for the different lengths of each month of a year in the calendar module of a watch. This type of watch usually shows the month and date, and sometimes the day of the week and the phase of the moon. It must be adjusted once a year.
Anti-magnetic
Mechanical movements can be influenced by the magnetic fields often found in common everyday places. This problem is generally countered by using nonmagnetic or anti-magnetic components in the movement.
Anti-reflection, Anti-reflective
A film created by steaming the crystal to eliminate light reflection and improve legibility.
Arbor
Bearing element of a gear(s) or balance, whose ends, called pivots, run in jewel holes or brass bushings.
Atmosphere (ATM)
Unit of pressure used in watch making to indicate water-resistance. ATM can be expressed in different ways: 10 ATM = 10 bars = 100 metres.
Atomic Time Standard
Provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division (in Boulder, Colorado) atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America and some “atomic” watches can receive them and correct to the exact time.
Automatic
A watch whose mechanical movement is wound automatically. A rotor makes short oscillations due to the movements of the wrist. Through a series of gears, oscillations transmit motion to the barrel, thus winding the mainspring progressively.
Automatic winding
A rotating weight, set into motion by moving the wrist, winds the spring barrel via the gear train of a mechanical watch movement. Automatic winding was invented during the pocket watch era in 1770 by Abraham-Louis Perrelet, who created a watch with a weight swinging back and forth (that of a pocket watch usually makes vertical movements contrary to a wristwatch). The first automatic – winding wristwatches, invented by John Harwood in the 1920’s, utilised so-called hammer winding, whereby a weight swung in an arc between two banking pins. The breakthrough automatic winding movement via rotor began with the ball bearing Eterna-Matic in the late 1940’s, and the technology hasn’t changed fundamentally since.
Automation
Figures, placed on the dial or case of watches, provided with parts of the body or other elements moving at the same time as the sonnerie strikes. The moving parts are linked, through an aperture on the dial or caseback, with the sonnerie hammers striking a gong.
B
Balance
Oscillating device that, together with the balance spring, makes up the movementh’s heart in as much as its oscillations determine the frequency of its functioning and precision.
Balance Spring
Component of the regulating unit that, together with the balance, determines the movement’s precision. The material used is mostly a steel alloy (e.g. Nivarox), an extremely stable metal compound. In order to prevent the system’s center of gravity from continuous shifts, hence differences in rate due to the watch’s position, some modifications were adopted. These modifications included Breguet’s overcoil (closing the terminal part of the spring partly on itself, so as to assure an almost perfect centering) and Philips curve (helping to eliminate the lateral pressure of the balance-staff pivots against their bearings). Today, thanks to the quality of materials, it is possible to assure an excellent precision of movement working even with a flat spring.
Bar or Cock
A metal plate fastened to the base plate at one point, leaving room for a gear wheel or pinion. The balance is usually attached to a bar called the balance cock.
Barrel
Component of the movement containing the mainspring, whose toothed rim meshes with the pinion of the first gear of the train. Due to the fact that the whole movement – made up of barrel and mainspring – transmits the motive force, it is also considered to be the very motor. Inside the barrel, the mainspring is wound around an arbor turned by the winding crown or, in the case of automatic movements, also by the gear powered by the rotor.
Base Metal
Any non-precious metal.
Battery
Device that converts chemical energy into electricity. Most watch batteries are silver oxide type delivering 1.5 volts.
Battery Life
The minimum period of time that a battery will continue to provide power to run the watch. Life begins at the point of manufacture when the factory initially installs the battery.
Battery Reserve Indicator
Some battery-operated watches have a feature that indicates when the battery is approaching the end of its life. This is often indicated by the second hand moving in two second intervals instead of each second.
Bearing
Part on which a pivot turns, in watches it is represented mostly by jewels.
Bevelling
Chamfering of edges of levers, bridges and other elements of a movement by 45º, a treatment typically found in high-grade movements.
Bezel
Top part of case, often in a shape of the ring surrounding the watch face, sometimes holds the crystal. It may be integrated with the case middle or may be a separate element. It is snapped or screwed on to the middle. The bezel typically has markings to indicate time zones, elapsed time (such as for scuba diving) or various other functions.
Blued Screw
Swiss watch making tradition dictates that a movement should contain blued screws for aesthetic reasons. Polished steel screws are heated, or tempered, to relax the steel, turning it a deep blue colour in the process.
Bracelet
A metal band attached to the case. It is called integral if there is no apparent discontinuity between case and bracelet and the profile of attachments is similar to the first link.
Bridge
Structural metal element of a movement – sometimes called cock or bar – supporting the wheel train, balance, escapement and barrel. Each bridge is fastened to the plate by means of screws and locked in a specific position by pins. In high-quality movements the sight surface is finished with various types of decoration.
Brushed, Brushing
Topical finishing giving metals a line finish, a clean and uniform look.
Buckle
Usually matching the case, it attaches the two parts of the leather strap around the wrist.
Feature usually at 2 o’clock and/or 4 o’clock position, to control special functions such as the chronograph or the alarm.
C
Cabouchon
Any kind of precious stone, such as sapphire, ruby or emerald, uncut and only polished, generally of a half-spherical shape, mainly used as an ornament of the winding crown or certain elements of the case.
Calendar, Annual
The automatic allowances for the different lengths of each month of a year in the calendar module of a watch. This type of watch also usually shows the month and date, and sometimes the day of the week and the phase of the moon.
Calendar, Full
Displaying date, day of the week and month on the dial, but needing a manual correction at the end of a month with less than 31 days. It is often combined with the moonphase.
Calendar, Perpetual
This is the most complex horology complication related to the calendar feature, as it indicates the date, day, month and leap year and does not need manual corrections until the year 2100 (when the leap year will be ignored).
Calibre
The Calibre term refers to each different type of watch movement e.g. ETA 2824-2. Watch movements come in various shapes to fit different case styles, such as round, tonneau, rectangular, rectangular with cut corners, oval and baguette. It is described in terms of its casing diameter, measured in millimetres. The round calibre is the most commonly encountered.
Cannon
An element in the shape of a hollow cylinder, sometimes also called pipe or bush, for instance the pipe of the hour wheel bearing the hour hand.
Carat (Karat)
Unit of gold fineness (and gemstone weight). Pure gold is 24k. 18k gold is 75% pure.
Carousel
Device similar to the tourbillon, but with the carriage not driven by the fourth wheel, but by the third wheel.
Carriage or Tourbillon Carriage
Rotating frame of a tourbillon device, carrying the balance and escapement. This structural element is essential for a perfect balance of the whole system and its stability, in spite of its reduced weight. As today's tourbillon carriages make a rotation per minute, errors of rate in the vertical position are eliminated. Because of the widespread use of transparent dials, carriages became elements of aesthetic attractiveness.
Case
Container housing and protecting the movement, usually made up of three parts: middle, bezel, and back. The most common case shapes are:
• Round
• Square
• Tonneau
• Round
• Square
• Tonneau
Center Second Hand
A sweep second hand, i.e. a second hand mounted on the center of the main dial.
Center-Wheel
The minute wheel in a going-train.
Champleve
Hand-made treatment of the dial or case surface. The pattern is obtained by hollowing a metal sheet with a graver and subsequently filling the hollows with enamel
Chapter-Ring
Hour-circle, i.e. the hour numerals arranged on a dial.
Chime
Striking-work equipped with a set of bells that may be capable of playing a complete melody. A watch provided with such a feature is called chiming watch.
Chronograph
A chronograph is a timepiece capable of recording elapsed time (like a stop-watch). A chronograph usually has several sub-dials with hands to indicate the elapsed seconds, minutes, and sometimes hours of a given event.
A standard chronograph has two pushers on the side of the case. The top one is used to start and stop the chronograph function and the bottom one to return the elapsed seconds, minutes, and hours hand to zero.
Chronometer
A high-precision watch. According to the Swiss law, a manufacture may put the word "chronometer" on a model only after each individual piece has passed a series of tests and obtained a running bulletin and a chronometer certificate by an acknowledged Swiss control authority, such as the COSC.
Circular Graining
Superficial decoration applied to bridges, rotors and pillar-plates in the shape of numerous slightly superposed small grains, obtained by using a plain cutter and abrasives. Also called Pearlage or Pearling.
Clasp
The attachment used to connect the two ends of the watch bracelet or strap around the wrist. Deployment Buckle - A three-folding enclosure, which secures the two ends of the bracelet and allows enough room for placing the watch on the wrist when fully deployed. When closed, the buckle covers the two-piece folding mechanism. Hook Lock – Two separate units each fitting on either end of the bracelet which allows the watch to be laid out. One end of the closure hooks onto the other to secure the two ends of the bracelet. Jeweller's Clasp - A closure that is generally used on better bracelets. Also allows it to lie flat. Sliding Clasp – Also a hook type method but allows for easy sizing of the bracelet by sliding up. Twist Lock – A closure similar to Jeweler's Clasp used on ladies jewelry bracelets.
Cloisonne
A kind of enamel work - mainly used for the decoration of dials - in which the outlines of the drawing are formed by thin metal wires. The colored enamel fills the hollows formed in this way. After oven firing, the surface is smoothed until the gold threads appear again.
Clous de Paris
Decoration of metal parts characterized by numerous small pyramids.
Cock
A metal plate fastened to the base plate at one point, leaving room for a gear wheel or pinion. The balance is usually attached to a bar called the balance cock.
Colimaconnage
Decoration with a spiral pattern, mainly used on the barrel wheel or on big-sized full wheels.
Column-Wheel
Part of chronograph movements, governing the functions of various levers and parts of the chronograph operation, in the shape of a small-toothed steel cylinder. It is controlled by pushers through levers that hold and release it. It is a very precise and usually preferred type of chronograph operation.
Complication
Additional function with respect to the manual-winding basic movement for the display of hours, minutes and seconds. Today, certain features, such as automatic winding or date, are taken for granted, although they should be defined as complications. The main complications are moonphase, power reserve, GMT, and full calendar. Further functions are performed by the so-called great complications, such as split-second chronograph, perpetual calendar, tourbilon device, and minute repeater.
Corrector
Pusher positioned on the case side that is normally actuated by a special tool for the quick setting of different indications, such as date, GMT, full or perpetual calendar
COSC
Abbreviation of “Contrôle Officiel Suisse des Chronomètres” the most important Swiss institution responsible for the functioning and precision tests of movements of chronometers. Tests are performed on each individual watch at different temperatures and in different positions before a functioning bulletin and a chronometer certificate are issued, for which a maximum gap of -4 to +4 seconds per day is tolerated.
Côtes Circulaires
Decoration of rotors and bridges of movements, whose pattern consists of a series of concentric ribs.
Côtes de Genève
Decoration applied mainly to high-quality movements, appearing as a series of parallel ribs, realized by repeated cuts of a cutter leaving thin stripes.
Countdown Timer
A function that lets the wearer keep track of how much of a pre-set period of time has elapsed. Some countdown timers sound a warning signal a few seconds before the time runs out.
Counter
Additional hand on a chronograph, indicating the time elapsed since the beginning of the measuring. On modern watches the second counter is placed at the center, while minute and hour counters have off-center hands in special zones, also called subdials.
Crown
The crown is a button which protrudes from the case that when turned can be used to wind the watch’s mainspring, set its hands and correct its date display.
Crown Wheel
Wheel meshing with the winding pinion and with the ratchet wheel on the barrel-arbor.
Crystal
The clean cover over the watch face. Three types of crystals are commonly found in watches: acrylic crystal, mineral crystal and sapphire crystal.
D
Deck Watch
A large-sized ship’s chronometer.
Deployment Buckle
A deployant, or fold-over clasp, allows for perfect strap closures through interlocking metal pieces
Depth Alarm
An alarm on a divers’ watch that sounds when the wearer exceeds a pre-set depth.
Depth Meter or Depth Sensor
A device on a divers’ watch that determines the wearer’s depth by measuring water pressure. It shows the depth either by analog hands and a scale on the watch face or through a digital display.
Deviation
A progressive natural change of a watch’s rate with respect to objective time. In case of a watch’s faster rate, the deviation is defined positive, in the opposite case negative.
Dial
Face of a watch, on which time and further functions are displayed by markers, hands, discs or through windows. Normally it is made of brass – sometimes silver or gold. Dials come in an almost limitless variety of shapes, decorations and materials.
Divers Watch
A diver’s watch is designed for underwater diving and will typically have a water resistance of around 200 to 300 m (660 to 980 ft). Dive watches will have a unidirectional rotating bezel with 15 or 20 minute markings and a screw-in crown and backplate.
Metal bracelets or rubber straps (not leather) are used as they are adequately water (pressure) resistant and able to endure the galvanic corrosiveness of seawater. Bracelets are often fitted with a divers extension deployment clasp by which the bracelet can be appropriately extended by approximately 20 mm to fit over a wetsuit.
Dive watches generally have a relatively thick sapphire crystal to enhance the pressure-resistance of the watch. Some watches intended for diving at great depths are fitted with a helium release or helium escape valve to prevent the crystal from being blown off by an internal build-up of helium pressure seeping into the watch case. This can happen when decompression stops during resurfacing are not long enough and a pressure difference builds up between the helium in the watch and the environment.
Metal bracelets or rubber straps (not leather) are used as they are adequately water (pressure) resistant and able to endure the galvanic corrosiveness of seawater. Bracelets are often fitted with a divers extension deployment clasp by which the bracelet can be appropriately extended by approximately 20 mm to fit over a wetsuit.
Dive watches generally have a relatively thick sapphire crystal to enhance the pressure-resistance of the watch. Some watches intended for diving at great depths are fitted with a helium release or helium escape valve to prevent the crystal from being blown off by an internal build-up of helium pressure seeping into the watch case. This can happen when decompression stops during resurfacing are not long enough and a pressure difference builds up between the helium in the watch and the environment.
E
Ébauche
Incomplete (jeweled or non-jeweled) watch movement without regulating organs, mainspring, dial and hands. It is also known as a blanc roulant.
Elapsed Time Rotating Bezel
A graduated rotating bezel used to keep track of elapsed time. The bezel can be turned so the wearer can align the zero on the bezel with the watch’s seconds or minutes hand. After a period of time passes, you can read the elapsed time off the bezel. This saves you having to perform the subtraction that would be necessary if you used the watch's regular dial.
Electroplating Process
Process of covering metal articles with a film of other metals. The article is immersed in a chemical solution; electric current (D.C.) flows through the solution from a piece of metal (anode) to the article (cathode), depositing metal thereon by electrolysis. See also PVD.
Endstone
Undrilled jewel, placed on the balance jewel with the tip of the balance-staff pivot resting against its flat surface, to reduce pivot friction. Sometimes used also for pallet staffs and escape wheels.
Engine-Turned
A surface decoration usually applied to the dial and the rotor using a grooving tool with a sharp tip, such as a rose engine, to cut an even pattern onto a level surface.
Equation of Time
Indication of the difference, expressed in minutes, between conventional mean time and real solar time. This difference varies from -16 to +16 seconds between one day and the other.
Escapement
A mechanism that is fitted between the gears and the regulating organ. The combination of the balance, balance spring, pallets and escape wheel, a subgroup which divides the impulses coming from the spring barrel into small, accurately proportioned doses. It guarantees that the gear train runs smoothly and efficiently.
F
Flange
The usually inclined ring that separates the crystal from the dial. The flange is sometimes equipped with features such as tachymetric scales and pulsometers.
Flinqué
Engraving on the dial or case of a watch, covered with an enamel layer.
Fluted
Said of surfaces worked with thin parallel grooves, mostly on dials or case bezels.
Fly-back
Feature combined with chronograph functions, that allows a new measurement starting from zero (and interrupting a measuring already under way) by pressing down a single pusher, i.e. without stopping, zeroing and restarting the whole mechanism. Originally, this function was developed to meet the needs of pilots.
Fold-over Clasp
Hinged and jointed element, normally of the same material as the one used for the case. It allows easy fastening of the bracelet on the wrist. Often provided with a snap-in locking device, sometimes with an additional clip or push-piece.
Fourth Wheel
The seconds wheel in going-train.
Frequency
Generally defined as the number of cycles per time unit; in horology it is the number of oscillations of a balance every two seconds or of its vibrations per second. For practical purposes, frequency is expressed in vibrations per hour (VPH). See also Vibration.
A conical part with a spiral groove on which a chain or cord attached to the barrel is wound. Its purpose is to equalize the driving power transmitted to the train. Almost all 16th, 17th and 18th Century watches have a fusee.
G
Glass
Thin plate of glass or transparent synthetic material, for protecting the dial of the watch.
Glucydur
Bronze and beryllium alloy used for high-quality balances. This alloy assures high elasticity and hardness values; it is non-magnetic, rustproof and has a very reduced dilatation coefficient, which makes the balance very stable and assures high accuracy of the movement.
GMT
GMT, or Greenwich Mean Time, is based on the globe being divided into 24 time zones as established in the London Meridian Conference of 1884. The zero meridian runs through the Royal Observatory in the London suburb of Greenwich. In contemporary watch terminology, GMT is often used to describe a wristwatch that displays a second time zone or a 24hour indication.
Gong
Harmonic flattened bell in a steel alloy, generally positioned along the circumference of the movement and struck by hammers to indicate time by sounds. Size and thickness determine the resulting note and tone. In watches provided with minute-repeaters, there are often two gongs and the hammers strike one note to indicate hours, both notes together to indicate quarters and the other note for the remaining minutes. In more complex models, equipped also with en-passant sonnerie devices, there may be up to four gongs producing different notes and playing even simple melodies.
A surface decoration usually applied to the dial and the rotor using a grooving tool with a sharp tip, to cut an even pattern onto a level surface. The finished effect is guilloché.
H
Hammer
Steel or brass element used in movements provided with a repeater or alarm sonnerie. It strikes a gong or bell (s).
Hand
Indicator for the analogue visualization of hours, minutes and seconds as well as other functions. Normally made of brass (rhodium-plated, gilded or treated otherwise), but also steel or gold. Hands are available in different shapes and sizes and take part in the aesthetic result of the whole watch. Early watches only had one hand for the hours.
The most common hand forms are:
• Baton – straight hands that taper to a fine point. These are the most basic and common hands used on most watches today.
• Daupine – are in the form of an elongated triangle
• Feuille – a hand in the shape of a leaf
• Poire
• Skeleton
• Spade
• Sword
The most common hand forms are:
• Baton – straight hands that taper to a fine point. These are the most basic and common hands used on most watches today.
• Daupine – are in the form of an elongated triangle
• Feuille – a hand in the shape of a leaf
• Poire
• Skeleton
• Spade
• Sword
Helium Valve
Valve inserted in the case of some professional diving watches to discharge the helium contained in the air mixture inhaled by divers. The helium escape valve prevents the crystal from being blown off by an internal build-up of helium pressure seeping into the watch case.
Hexalite
An artificial glass made of a plastic resin. Back in the 1960’s, many watches used either mineral glass or acrylic crystals. These are not difficult to scratch, but very inexpensive to replace. Now though, most all luxury watches use the highly scratch resistant synthetic sapphire crystals, there are some styles/brands that use the Hesalite (a trade name for an advanced synthetic (acrylic) crystal). The reason for this is directly related to the watch's certification for use in high stress/impact situations. While sapphire crystals are less prone to scratching, they can be shattered. When shattered, they break into tiny fragments that would be hazardous in some environments e.g. NASA specify hesalite crystal for all watches going into space. The Hesalite crystal is shatterproof so is maintained on some specific models as a safety feature.
Hunter Caliber
A caliber characterized by the seconds hand fitted on an axis perpendicular to the one of the winding stem.
Incabloc is a shock-absorber system used in mechanical watches which helps prevent damage from shocks to the balance pivots. Thanks to a retaining spring system, it assures an elastic play of both jewels, thus absorbing the movements of the balance-staff pivots when the watch receives strong shocks. The return to the previous position is due to the return effect of the spring. If such a system is lacking, the shock forces exert an impact on the balance-staff pivots, often causing bending or even breakage. Most high-quality mechanical watches made today use the Incabloc system.
J
Jewel
To minimize friction, the hardened steel tips of a movement’s rotating gear wheels (called pinions) are lodged in synthetic rubies (fashioned as polished stones with a hole) and lubricated with a very thin layer of special oil. These synthetic rubies are produced in exactly the same way as sapphire crystal using the same material.
Jumping Hour
Feature concerning the digital display of time in a window. The indication changes almost instantaneously at every hour.
K
Kinetic
Refers to a particular collection of watches by our manufacturing partner Seiko. This innovative technology has a quartz movement that does not use a battery. Movement of the wrist charges a very efficient capacitor which powers the quartz movement. Once the capacitor is fully charged, men’s models will store energy for 7-14 days without being worn. Ladies models store energy for 3-7 days. Of course, if the watch is worn every day the capacitor is continually recharged. The watch alerts the owner to a low capacitor charge when the seconds hand starts to move in two second intervals. Some of Seiko’s Kinetic watches have see-through case backs, that use a clear, Hardlex crystal watch back to enable the wearer to view the kinetic movement.
Kinetic Auto Relay
Refers to a specific line of watches, within the Kinetic collection, invented by our manufacturing partner Seiko. A Kinetic Auto Relay watch is powered by human movement, however when it senses inactivity for three days, it puts itself into suspended animation to conserve energy. It can be re-activated with a few shakes of the wrist. It automatically resets itself to the exact time after to up to four years of dormancy.
L
Lap Timer
A chronograph function that lets the wearer time segments of a race. At the end of a lap, the timer can be stopped, which then returns to zero to begin timing the next lap.
Leap-Year Cycle
Leap or bissextile years have 366 days and occur every 4 years (with some exceptions, Calendar, Gregorian). Some watches display this datum.
Line
Ancient French measuring unit maintained in horology to indicate the diameter of a movement. A line equals 2.255mm. Lines are not divided into decimals; therefore, to indicate measurements inferior to the unit, fractions are used.
Liquid Crystal Display or LCD
A digital watch display that shows the time electronically by means of a liquid held in a thin layer between two transparent plates. All LCD watches have quartz movements.
Lubrication
To reduce friction caused by the running of wheels and other parts. There are points to be lubricated with specific low-density oils such as the pivots turning inside jewels, the sliding areas between levers, and the spring inside the barrel which requires special grease, as well as numerous other parts of a movement.
Lug
Double extension of the case middle by which a strap or bracelet is attached. Normally, straps and bracelets are attached with removable spring bars.
Luminescent or Luminous
Having the property to emit light rays. Zanuti watches use Super-LumiNova, a photo-luminescent non-radioactive material with a long period of phosphorescence. It reaches up to 100 times the brightness of Tritium. Tritium was the original, radioactive, substance used to coat hands, numerals and hour markers on watch dials to make reading the time in the dark possible. This type of phosphorescent pigment, often called lume, operates like a light battery. After sufficient activation by sunlight or artificial light, they glow in the dark for hours. This activation and subsequent light emission process can be repeated again and again, and the material does not suffer any practical aging. LumiNova is a registered trademark of Japanese brand Nemoto and Co. Ltd.
M
Mainspring
The mainspring, located in the spring barrel, stores energy when tensioned and passes it on to the escapement via the gear train as the tension releases. Today, mainsprings are usually made of Nivaflex, an alloy invented by Swiss engineer Max Straumann in the early 1950’s. This alloy basically comprises of iron, nickel, chrome, cobalt and beryllium.
Manual
A mechanical movement that is wound by hand using the winding crown. The motion transmitted from the user’s fingers to the crown is forwarded to the movement through the winding stem, from this to the barrel through a series of gears and finally to the mainspring.
Manufacture
Most experts agree that the term, which is from Latin and means “made by hand” should be used for a company that manufactures at least one calibre, or extremely important parts of it such as the base plate, on the premises. While ten years ago this constituted only a handful of companies in Switzerland and Germany today’s competitive market has forced a number of others to invest in developing their own movements.
Marine Chronometer
A large-sized chronometer watch enclosed in a box (therefore also called box chronometer) mounted on gimbals and used on board ships, to determine the respective longitude.
Meantime
The mean time of the meridian of the Greenwich Observatory, considered the universal meridian, is used as the standard of the civil time system, counted from midnight to midnight.
Mechanical Movement
A movement powered by a mainspring, working in conjunction with a balance wheel. (See also 'Movement' term below)
Military Time or 24hr Time
When time is measured in 24-hour segments. To convert 12-hour time into 24-hour time, simply add 12 to any p.m. time. To convert 24-hour time into 12-hour time, subtract 12 from any time from 13 to 24.
Mineral Crystal or Mineral Glass
Watch crystal that has been tempered (heat treated) to increase its hardness and scratch resistance.
Minute Repeater
Mechanism indicating time by acoustic sounds. Contrary to the watches provided with en-passant sonnerie devices, that strike the number of hours automatically, repeaters work on demand by actuating a slide or pusher positioned on the case side. Repeaters are normally provided with two hammers and two gongs: one gong for the minutes and one for the hours. The quarters are obtained by the almost simultaneous strike of both hammers. The mechanism of the striking work is among the most complex complications.
The minute repeater feature was very much in vogue before displays became common to allow people to know the time in the dark. They are also useful for the visually challenged. Today in many watches it is a feature that adds to the novelty of the watch.
The minute repeater feature was very much in vogue before displays became common to allow people to know the time in the dark. They are also useful for the visually challenged. Today in many watches it is a feature that adds to the novelty of the watch.
Mono (Single) Pusher Chronograph
A chronograph watch that works by using a single button. The majority of stop watches need two buttons, one to start and stop and another one to reset. A Mono Pusher complication manages to do all three operations on the same button.
Moonphase
A function available in many watches, usually combined with calendar-related features. The moonphase disc advances one tooth every 24 hours. Normally, this wheel has 59 teeth and assures an almost perfect synchronization with the lunation period, i.e. 29.53 days (in fact, the disc shows the moonphases twice during a single revolution). However, the difference of 0.03 days, i.e. 44 minutes each month, implies the need for a manual adjustment every two and a half years to recover one day lost with respect to the real state of moonphase. In some rare cases, the transmission ratio between the gears controlling the moonphase are calculated with extreme accuracy so as to require manual correction only once in 99 years.
Mother of Pearl
Iridescent, milky interior shell of the fresh water mollusc that is sliced thinly and used on watch dials. While most have a milky white lustre, mother-of-pearl also comes in other colours such as silvery grey, grey blue, pink, and salmon.
The entire mechanism of a watch. Movements are divided into two great families: quartz and mechanical; the latter are available with manual or automatic winding devices. “Anatomically speaking” the movement comprises the Ébauche, the regulating parts and other components (springs, jewels, pivots, pinions, screws, shock-absorbers, etc.).
N
Nivarox
Trade name (from the producer’s name) of a nickel iron alloy, resisting magnetization, used for modern self-compensating balance springs. The level of this material is indicated by the numeral following the name in decreasing value from 1 to 5. As a trade name, Nivarox is a German acronym for “Nicht variabel oxydfest” (G.) or “Non-Variable Non-Oxidizing” (E.). The Nivarox alloy is a used mainly in the watch industry, but also in certain medical equipment and surgical instruments.
O
Observatory Chronometer
An observatory-tested precision watch that obtained the relevant rating chronometer certificate.
Oscillation
Complete oscillation or rotation movement of the balance, formed by two vibrations. When a pendulum or balance oscillates it moves between two extreme positions (A' and A''). The movement from one of these positions to the other and back equals one oscillation. Usually a balance produces 9,000 oscillations an hour, equivalent to 18,000 vibrations. 1 oscillation = 2 vibrations
P
Pallets
Device of the escapement transmitting part of the motive force to the balance, in order to maintain the amplitude of oscillations unchanged by freeing a tooth of the escape wheel at one time.
Pillar-Plate or Main Plate
A metal platform having several tiers for the gear train. The base plate of a movement usually incorporates the dial and carries the bearings for the primary pinions of the “first floor” of a gear train.
Pinion
Combines with a wheel and an arbor to form a gear. A pinion has less teeth than a wheel and transmits motive force to a wheel. Pinion teeth (normally 6 to 14) are highly polished to reduce friction to a minimum.
Pivot
End of an arbor turning on a jewel support. As their shape and size can influence friction, the pivots of the balance-staff are particularly thin and, hence, fragile, so they are protected by a shockproof system.
Polished Finish
Brilliant metal surface obtained on the watch case with fine abrasive. Compare with brushed finish.
Power Reserve
Duration, in hours, of the residual functioning autonomy of a movement after it has reached the winding peak. The duration value is displayed by an instantaneous indicator: analogue (hand on a sector) or digital (through a window). The related mechanism is made up of a series of gears linking the winding barrel and hand. Recently, specific modules were introduced which may be combined with the most popular movements.
Precision
Accuracy rate of a watch, a term difficult to define exactly. Usually, a precision watch is a chronometer of which accuracy-standard is certified by an official watch-rating bureau.
Pusher, Push-Piece or Push Button
Mechanical element mounted on a case for the control of specific functions. Generally, pushers are used in chronographs, but also with other functions.
PVD
Abbreviation of Physical Vapour Deposition, a plating process consisting of the physical transfer of substance by bombardment of electrons. Though PVD coatings are typically only a few microns thick the molecules bond to the surface of the metal in such a way that they are nearly impossible to remove once applied. It reduces wear of bracelets, crowns, bezels and virtually eliminates reflective glare.
Q
R
Ratchet Wheel
Toothed wheel prevented from moving by a click pressed down by a spring.
Regulating Unit
Made up by balance and balance spring, governing the division of time within the mechanical movement, assuring its regular running and accuracy. As the balance works like a pendulum, the balance spring's function consists of its elastic return and start of a new oscillation. This combined action determines the frequency, i.e. the number of vibrations per hour, and affects the rotation speed of the different wheels. In fact the balance, by its oscillations, at every vibration (through the action of the pallets), frees a tooth of the escape wheel (see escapement). From this, motion is transmitted to the fourth wheel, which makes a revolution in one minute, to the third and then the centre wheel, the latter making a full rotation in one hour. However, everything is determined by the correct time interval of the oscillations of the balance.
Regulator
Regulating the functioning of a movement by lengthening and shortening the active section of the balance spring. It is positioned on the balance-bridge and encompasses the balance spring with its two pins near its fixing point on the bridge itself. By shifting the index, the pins also are moved and, by consequence, the portion of the balance spring capable of bringing the balance back is lengthened or shortened by its elastic force.
The shorter it is, the more reactive it tends to be and the more rapidly it brings the balance back and makes the movement run faster. The contrary happens when the active portion of the balance spring is lengthened. Given today's high frequencies of functioning, even slight index shifts entail daily variations of minutes. Recently, even more refined index-regulation systems were adopted (from eccentric to micrometer screws) to limit error margins to very few seconds per day.
The shorter it is, the more reactive it tends to be and the more rapidly it brings the balance back and makes the movement run faster. The contrary happens when the active portion of the balance spring is lengthened. Given today's high frequencies of functioning, even slight index shifts entail daily variations of minutes. Recently, even more refined index-regulation systems were adopted (from eccentric to micrometer screws) to limit error margins to very few seconds per day.
Regulator display
A Regulator display separates the minute and hour hands onto a separate axial & sub-dial. Before the advent of more modern methods of checking for the accuracy of a watch, watchmakers used a regulator clock where the hour, minute and second hands are operated separately, to check their work.
More recently, mechanical regulator watches were used during Second World War night-time bombing missions when greater precision was essential
More recently, mechanical regulator watches were used during Second World War night-time bombing missions when greater precision was essential
Retrograde
Said of a hand that, instead of making a revolution of 360º before starting a new measurement, moves on an arc scale (generally of 90º to 180º and at the end of its trip comes back instantaneously. Normally, retrograde hands are used to indicate date, day or month in perpetual calendars, but there are also cases of retrograde hours, minutes or seconds. Unlike the case of the classical indication over 360º the retrograde system requires a special mechanism to be inserted into the basic movement.
Rotating Bezel
A bezel that can be turned. Different types of rotating bezels perform different time keeping and mathematical functions.
Rotor
The rotor is the component that keeps an automatic watch wound. The kinetic motion of this part, which contains a heavy metal weight around its outer edge, winds the mainspring.
S
Sapphire Crystal
Synthetic sapphire crystal is a virtually scratchproof material with a hardness of 9 on the Mohs scale which means only a diamond is harder. The material is known to gemmologists as aluminium oxide or corundum, can be colourless (corundum), red (ruby), blue (sapphire) or green (green sapphire). It is “grown” using a method invented by Auguste Victor Louis Verneuil in 1902 whereby a process that usually takes a thousand years to complete is accelerated to just a few hours, hence the use of the term synthetic.
Scale
Graduation on a measuring instrument, showing the divisions of a whole of values, especially on a dial, bezel. The scales mostly used in horology are related to the following measuring devices: tachometer (indicating the average speed), telemeter (indicating the distance of a simultaneously luminous and acoustic source, e.g. a cannon-shot or a thunder and related lightning), pulsometer (to calculate the total number of heartbeats per minute by counting only a certain quantity of them). For all of these scales, measuring starts at the beginning of the event concerned and stops at its end; the reading refers directly to the chronograph second hand, without requiring further calculations.
Screw Balance
Before the invention of the perfectly weighted balance by use of a smooth ring, balances were fitted with weighted screws to get the exact impetus desired. Today a screw balance is a subtle sign of quality in a movement due to its costly construction.
Second Time-Zone Indicator
An additional dial that can be set to the time in another time zone. It lets the wearer keep track of local time and the time in another country simultaneously. See also GMT and world time
Sector
A circular sector, also known as a “pie piece”, is the portion of a circle (or dial) enclosed by two radii.
Self-Winding (Automatic)
A watch whose mechanical movement is wound automatically. A rotor makes short oscillations due to the movements of the wrist. Through a series of gears, oscillations transmit motion to the barrel, thus winding the mainspring progressively.
Shockproof or Shock-Resistant
Watches provided with shock-absorber systems (e.g. Incabloc) help prevent damage from shocks to the balance pivots. Thanks to a retaining spring system, it assures an elastic play of both jewels, thus absorbing the movements of the balance-staff pivots when the watch receives strong shocks. The return to the previous position is due to the return effect of the spring. If such a system is lacking, the shock forces exert an impact on the balance-staff pivots, often causing bending or even breakage.
Slide
Part of a mechanism moving with friction on a slide-bar or guide.
Small Second
Time display in which the second hand is placed in a small subdial.
Solar Time
The time standard referred to the relative motion of the Earth and the Sun governing the length of day and night. The true solar day is the period measured after the Sun appears again in the same position from our point of observation. Due to the non-uniform rotation of the Earth around the Sun, this measure is not regular. As an invariable measure unit, the mean solar day corresponds to the average duration of all the days of the year.
Solstice
The time when the sun is farthest from the equator, i.e. or the Northern Hemisphere on June 21st (Summer solstice) and December 21st (Winter solstice).
Split-Second Chronograph
Also known in the watch industry by its French name - Rattrapante. A watch with two second hands, one of which can be blocked with a special dial train lever to indicate an intermediate time while the other continues to run. When released, the split-seconds hand jumps ahead to the position of the other second hand.
Spring Barrel
The spring barrel contains the mainspring. It turns freely on an arbor, pulled along by the toothed wheel generally doubling as its lid. This wheel interacts with the first pinion of the movement’s gear train. Some movements contain two or more spring barrels for added power reserve.
Stopwatch
A watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a chronograph.
Stopwork
Traditional device (now obsolete) provided with a finger piece fixed to the barrel arbor and a small wheel in the shape of a Maltese cross mounted on the barrel cover, limiting the extent to which the barrel can be wound.
Super-LumiNova
A photo-luminescent non-radioactive material with a long period of phosphorescence. It reaches up to 100 times the brightness of Tritium. Tritium was the original, radioactive, substance used to coat hands, numerals and hour markers on watch dials to make reading the time in the dark possible. See also Luminescent.
Sweep Second Hand
A centre second hand (i.e. a second hand mounted on the centre of the main dial) usually rotating at a frequency of 2 to 5 Hertz.
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T
Tachometer or Tachymeter
A scale on the dial, flange, or bezel (as in the case of our 2020 Limited Edition) of a chronograph that, in conjunction with the second hand, gives the speed of a moving object. A tachymeter takes a value determined in less than a minute and converts it into miles or kilometres per hour. For example, the wearer could measure the time it takes a car to pass between two mile markers on a road. When the car passes the second marker, the second hand will be pointing to the car’s speed in miles per hour on the tachometric scale.
Thermo-compensation
Quartz watches split time by exploiting the electromechanical phenomenon known as Piezoelectricity. When a continuous electrical current runs through it, the quartz crystal starts resonating at a constant frequency. Crystal oscillators for watches are manufactured to vibrate at 215Hz (32,768 Hz), a frequency that will then be halved 16 consecutive times by a processor to obtain the second (unit of time). The problem with quartz crystals is that they are easily affected by temperature: they tend to vibrate faster in heat and slower in cold. As a consequence, quartz watch can have between -10 to +15 sec. variations per month. Bearing in mind that mechanical watches can variate by -10 to + 15 sec. per day, the quartz oscillator is still far more accurate than the anchor escapement found in mechanical watches. The solution ETA engineers found was to add a thermometer that constantly feeds information to the processor, allowing it to compensate for errors caused by temperature. As a consequence, movements using this technology can be accurate to -10 to +15 sec. per year.
Time Zones
The 24 equal zones into which the surface of the Earth is conventionally divided, each limited by two meridians. The distance between two adjacent zones is 15º or 1 hour. Each country adopts the time of its zone, except for countries with more than one zone. The universal standard time is that of the zero zone, the axis of which is the Greenwich meridian.
Titanium
Titanium is an environmentally friendly, natural metal that is 40% stronger and 30% lighter than stainless steel. It is hypoallergenic because it is nickel-free. It is perfect for water sport enthusiasts as it is extremely resistant to salt water and other forms of corrosion and able to withstand extreme temperatures. Many titanium watches are further enhanced with a glass coating for increased scratch resistance.
Tonneau
Particular shape of a watchcase, imitating the profile of a barrel, i.e. with straight, shorter, horizontal sides and curved, longer, vertical sides.
Tourbillon
A technically demanding device invented by Abraham Louis Breguet in 1801 to compensate for the interference of gravity on the balance of a pocket watch, thus improving its rate. In a tourbillon (from the French word for whirlwind), the entire escapement is mounted on an epicyclic train in a “cage” and rotated completely on its axis over regular periods of time, usually once a minute. This superb horological highlight, whilst being completely unnecessary for a wristwatch, is seen as a sign of technological know-how in the modern era.
Tritium
Slightly radioactive material that collects light energy and is used to coat hands, numerals, and hour markers on watch dials in order to make reading the time in the dark possible. Watches bearing tritium must be marked as such, with the letter T on the dial near 6 o'clock. It is gradually being replaced by nonradioactive materials such as Super-LumiNova and Traser due to medical misgivings and expected governmental regulation of its use.
Two-Tone
A term use to indicate that a watch has both "silver" and "gold" tone color which may or may not be genuine gold or silver.
U
Uni-directional Rotating Bezel
A rotating bezel, often found on divers’ watches, that moves only in a counterclockwise direction and makes it easy to measure elapsed time. It is particularly useful for divers so they cannot accidentally rotate it in the wrong direction, which could cause them to miscalculate their dive times. Most divers’ watches are ratcheted, so that they lock into place for greater safety and precision.
Universal Time
The mean solar time of the Greenwich meridian, counted from noon to noon, often confused with the mean time notion.
V
Variation
In horology the term is usually referred to the variation of the daily rate, i.e. the difference between two daily rates specified by a time interval.
Vibration Frequency (VPH)
The ring-shaped balance swings around its own axis and acts as the ruling organ of the movement’s escapement. Its amplitude (normally about 300 degrees) is restricted by the very thin balance spring, which also provides for the reversing of its direction of rotation. The frequency of the alternating vibrations is measured in Hertz (Hz) or in the more usual vibrations per hour (VPH).
The most common frequency for modern mechanical wristwatch movements is 28,800 vph (or 4 Hz). A watch ticking at 4Hz makes 4 oscillations per second, or 8 semi-oscillations (or vibrations) per second. There are 60 seconds in a minute, so this watch would tick at 480 semi-oscillations (or vibrations) per minute. Multiplying the 480 vibrations per minute by the 60 minutes in an hour yields the 28,800 VPH figure. Since this watch ticks 8 times per second, a chronograph in a 28,800 VPH watch can time events to the nearest 1/8 of a second.
The most common frequency for modern mechanical wristwatch movements is 28,800 vph (or 4 Hz). A watch ticking at 4Hz makes 4 oscillations per second, or 8 semi-oscillations (or vibrations) per second. There are 60 seconds in a minute, so this watch would tick at 480 semi-oscillations (or vibrations) per minute. Multiplying the 480 vibrations per minute by the 60 minutes in an hour yields the 28,800 VPH figure. Since this watch ticks 8 times per second, a chronograph in a 28,800 VPH watch can time events to the nearest 1/8 of a second.
W
Water Resistant or Waterproof
The ability to withstand contact with water without suffering damage. Watches have various degrees of water resistance. Usually measured in increments of one atmosphere (ATM or bar, equal to 10 metres of water pressure) or metres and is often noted on the dial or case back.
A water resistance level of 30 metres means the watch can withstand splashes of water. A level of 50 metres means that it can be worn for swimming in shallow depths. A level of 100 metres means it can be worn snorkelling and a level of 300 metres or more means it can be worn scuba diving.
A water resistance level of 30 metres means the watch can withstand splashes of water. A level of 50 metres means that it can be worn for swimming in shallow depths. A level of 100 metres means it can be worn snorkelling and a level of 300 metres or more means it can be worn scuba diving.
Wheel
A circular component, mostly toothed, combines with an arbor and a pinion to make up a gear. The wheel rotates around an axis and its function is to transmit power or motion. Wheels are normally made of brass, while arbors and pinions are made of steel. The wheels between barrel and escapement make up the so-called train.
Winding Stem
Element transmitting motion from the crown to the gears governing manual winding and setting.
Window
Aperture in the dial, that allows reading the underlying indication, mainly the date, but also indications concerning a second zone’s time or jumping hour.
World Time
Additional feature of watches provided with a GMT function, displaying the 24 time zones on the dial or bezel, each zone referenced by a city name, providing instantaneous reading of the time of any country.
Y
Yacht Timer
A Yacht Timer complication is a type of movement that includes a countdown timer, specifically designed to display the time left to the start of a regatta or yacht race.
Z
Zone
Small additional dial or indicator that may be positioned, or placed off-centre on the main dial, used for the display of various functions (e.g. second counters).
Zodiac dial
A dial or sub-dial featuring a circular belt with the ecliptic in the middle, containing the twelve constellations through which the sun seems to pass in the course of a year.
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