Ever wondered what that thing is in your watch, or perhaps you’ve heard a word mentioned a few times and you just don’t know what it is?
Hopefully our watch glossary is useful – if you think something is missing, please do get in touch to let us know and we’ll be sure to add it!!
Acrylic Crystal (or Glass)
A plastic, or polymer, made from acrylate. It is a less expensive, soft and pliable material, which is also fairly durable – it does tend to scratch easier than other more expensive options though.
Alarm
A function that will make a sound or vibration at a time set in advance.
Altimeter
Used for measuring altitude, or height above sea level. Recording ascent and descent. A useful piece of equipment for outdoor activities (climbing, walking, mountaineering), but also for aviators.
Ana-digi Display (or Duo Display)
A display that shows the time using analogue display (hour and minute hands) and with a digital number display.
Analogue
A watch that uses hands to indicate the time.
Anglage (or Bevelling)
A hand finishing technique and often an indication of fine watchmaking. A 45° chamfer is applied to watch bridges and plates by hand and given a highly polished finish, demonstrating the skill of the watchmaker.
Annual Calendar
A watch which shows the day, date, and month and does not need to be adjusted every month, as it deals with the changing of months and automatically adjusts the date accordingly.
Anti-magnetic
A watch that can maintain accurate timekeeping when exposed to a certain level of magnetic field. The watch must continue running during the exposure and must not exceed +/- 30 seconds per day after being exposed to a significant magnetic field.
Anti-reflective Coating
A coating that is applied to the crystal of some watches in order to prevent it from reflecting light. There are multiple compounds readily available for application of watch crystals which differ in terms of AR performance, durability and legibility.
Aperture
A small opening found on the dial of some watches, where certain indications or movement parts can be seen through (for example, the date, or tourbillon).
Arabic Numerals
The most common symbols for numbers on a watch. It usually refers to the standard numerical digits of 1 – 12.
Ardillon Buckle
A traditional pin buckle for fastening a strap. One end of the strap goes through a buckle and the pin is used to secure it.
Argenté Dial
A solid silver dial, with a (plated) silvery looking finish.
Auto Repeat Countdown Timer
A countdown timer that resets back to the pre-set time, as soon as the time has elapsed and starts the timer again. This function is repeated continuously until the stop button is pushed.
Auto Rotor (or Oscillating Weight)
A component which is attached to the watch movement and connected to the mainspring by an intricate series of gears. As it swings and rotates with the wearer’s wrist movements, it winds the mainspring as it turns and ultimately feeds energy to make the watch function. Usually it is a semi-circlular metal weight.
Automatic Winding (or Self-winding/Perpetual)
Winding that occurs through movement of the wearer, rather than by turning the crown and winding stem. A component turns in response to motion, winding up the watch’s mainspring, creating power.
Baguette Case
An elongated rectangular, or an oval shaped watch case.
Bakelite
Is the trademark for a synthetic resin known as phenol-formaldehyde. It is a hard and resistant synthetic plastic that is shatterproof and resistant to things like acid and electricity.
Balance Cock
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Balance Spring (or Hairspring)
A very fine spring in a mechanical watch that causes the recoil of the balance wheel. The length and adjustment of its length regulates the accuracy of the timekeeping.
Balance Wheel
The part of a mechanical watch movement that oscillates, dividing time into equal segments. This is the regulating mechanism that controls the watch’s timekeeping accuracy.
Bar
A measure of pressure, which gives an indication of the water resistance test level of a watch and the expectations of depth. 1 BAR = 100m, 2 BAR = 200m, 3 BAR = 300m and so on.
Barrel
A drum that holds the mainspring in a mechanical watch. The toothed rim of the barrel drives the train.
Bevelling (or Anglage)
A hand finishing technique and often an indication of fine watchmaking. A 45° chamfer is applied to watch bridges and plates by hand, demonstrating the skill of the watchmaker.
Bezel
The ring on the outside of the watch case, around the dial, or the rim that holds the watch glass. It may have calibrated markings, especially on sports or divers watches and usually has a coin style edge for grip.
Bi-directional Rotating Bezel
A bezel that can be moved clockwise or anti-clockwise. It is used for keeping track of elapsed time.
Black polish
A perfectly smooth polished surface, that is done by hand, by scrubbing the flat surface with special diamond pastes. Light reflects over it, giving it a black effect.
Blanc Roulant (or Ébauche)
The main elements of a watch movement without its regulating organ, mainspring, dial or hands. This is often what is sold to watch manufacturers, when they will create their own additional parts.
Bracelet
The metal strap that goes around the wearer’s wrist. A watch bracelet is often made up of flexible, separate links that can be removed to adjust the bracelet’s length.
Breguet Numerals
Numbers on a dial that have bold black lines tapering to fine points and a slight slant just less than italic. The result is a font with a classic, antique look without losing legibility
Breguet Spring
A small haispring which has a bent terminal curve and through its elasticity, regulates the oscillations of the balance.
Bridge
A part that is fixed to the main plate to form the upper bearing point for at least one wheel axis (pivot point) frame of a watch movement.
Brushed Finish (or Satin Finish)
A finish applied to metals, by making uniform scratches all in the same direction; either in straight lines, or in a circular pattern. Different co
Bund Pad
Usually in an all-in-one strap format, this is a protective leather pad which sits under the watch case. Originally used by German WW2 pilots, to protect their wrists from extreme heat and cold.
Calendar
A function that indicates day of the month, as well as day of the week and the year in some instances.
Calibre (or Caliber)
The internal mechanism of a watch or clock, which is now used to designate a specific model of movement. Originally it was only used to refer to the size of a movement.
California Dial (or Roman-Arabic Dial)
When Roman numerals and Arabic numerals can be found on the same dial
Cambered
This refers to an arched or curved dial or bezel.
Carat
A unit of weight used to measure the size of a gemstone such as a diamond and equates to 200 milligrams. As an example, a 4 carat diamond, weighs 800 milligrams.
Carbon Fibre
An organic polymer material consisting of thin, strong crystalline filaments of carbon to create a long thin string. About 90% of the carbon fibres produced are made from polyacrylonitrile (PAN); the remaining 10% are made from rayon or petroleum pitch. All of these materials are organic polymers. It is extremely light and strong.
Carillon
A minute repeater with 3 gongs.
Carrure
The central part of the watch case that houses the movement.
Case
The housing that contains the movement and other parts of a watch. Stainless steel is most commonly used although titanium, platinum, ceramic, gold and silver can be found, amongst others. Less expensive watches are often made of brass and plated with gold-coloured or silver-coloured metals.
Centre Seconds
A seconds hand that is fixed at the centre of the dial.
Ceramic
Any material that is solid, inorganic and non-metallic; usually made using a combination of materials, either compounds of metals, metalloids or non-metals (or all of them together), to create different versions of ceramic. Modern ceramics contain a mix of ionic and covalent bonds to ensure for the most hardwearing and durable finish.
Ceramic Case
A watch case that is made entirely from ceramic.
Ceramic Dial
A dial (or part of a dial) that is made from ceramic
Champlevé
An enamelling technique used for watch dials, where troughs or cells are carved, etched, die struck, or cast into the surface of a metal object and then filled with vitreous enamel and fired.
Chapter Ring
A way to indicate time and usually on the outer edge of the dial, it can be mounted or decorated on the dial, with tracks or indices.
Chemin de Fer
A French word meaning “railway track”, which is a minute marker track around the dial, in the style of a railway track and is used mainly in classically designed watches.
Chronograph
A watch that tells the time and acts as a stopwatch, without interfering with the ability to tell the time. There are many different styles and they can have different functions. For example, a chronograph used in conjunction with specialised scales on the watch dial or bezel, can determine speed and distance; whilst some can time more than one event, lap, or participant at a time.
Chronometer
A watch that has been vigorously tested in various positions and temperatures to ensure that it meets high standards of accuracy demanded by the COSC. To be called a chronometer, the mechanical movement must achieve an average rate of between -4/+6 seconds per day.
Clasp
Generally, two metal hinges that open to the right and left of each other, but stay joined, in order to slide the watch off the wrist, without fully unfastening the strap or bracelet. Some clasps have a side button system, whilst others are clicked in place manually.
Clous de Paris
A guilloché technique which features continuous intersecting lines to form hundreds of tiny square pyramids. It provides a bumpy relief which gives a sense of depth to the dial.
Co-axial Escapement
An escapement mechanism that functions with a system of three pallets that separate the locking function from the impulse. It uses radial friction at the impulse surfaces, rather than sliding friction, as this significantly reduces the sliding friction of the pallet stones over the teeth of the escape wheel and eliminates the need to lubricate the pallets. This provides greater accuracy over time, as well as potentially less servicing for the movement.
Column Wheel
The component used in a chronograph to control functions. A column wheel is present when the chronograph is fully integrated into the movement, rather than a chronograph movement added to a base calibre.
Complications (or Functions)
The various different tasks a watch can perform other than timekeeping, such as chronograph and countdown timer.
Constant Force Mechanism (or Remontoire)
A mechanism that regulates and distributes the energy that is passed through the escapement, the purpose being to keep the rate even and precise, regardless whether the watch is fully wound or the power is almost diminished.
COSC
Is the official testing office for chronometers (Contrôle Officiel Suisse des Chronomètres) and the world’s largest issuer of chronometer certificates. The movement rates are tested and if they meet the specifications required, a COSC certification will be granted.
Côtes de Genève (or Geneva Stripes)
A traditional Swiss decoration on watch movements, made by intricately engraving tiny, angled scratches in a systematic manner onto the metal, to create what looks like parallel stripes.
Countdown Timer
This allows the wearer to know how much of a pre-set time has passed. Some timers sound a warning a few seconds before the pre-set time has elapsed.
Crown (or Winding Stem)
The grooved button on the outside of the case, used for setting the hands on a watch, and the day and date, where applicable. It is also used for winding the mainspring of a mechanical watch.
Crystal
This is the clear cover above the watch dial. It could be made of glass, plastic, mineral crystal or sapphire crystal.
Cushion Case
A square shaped case, with softly rounded corners.
Cyclops
The magnifying lens found on the crystal of some watches, usually over the date window.
Day/Date
A watch that shows the day and the date.
Day/Night Indicator
An indication that shows whether a time is during the day or at night. A world timer often has a band indicating the cities that are in daylight and which are in night hours.
Dead Beat Seconds (or Jumping Seconds)
A mechanical movement with a hairspring and balance, whose second hand beats at 1Hz (or one beat a second), rather than appearing to smoothly move around the dial.
Deployment (or Deployant) Buckle or Clasp
Two curved strips of hinged metal on a watch strap that fastens the strap tightly to the wrist.
Dial
This is the face of the watch.
Digital Display
A watch that shows the time in numbers, or digits, rather than by using hands and a dial. Liquid crystal display (LCD) is commonly used in these displays.
Dive Watch
A tool watch specifically designed to use while doing water sports, with a water resistance of 1 bar (100m) or more.
Double Chronograph
A timepiece with two stopwatch mechanisms, which allows the measurement of two separate events concurrently and/or comparatively.
Dual Timer
A watch that shows local time and the time in at least one other time zone.
Duo Display (or Ana-digi Display)
A display that shows the time using analogue display (hour and minute hands) and with a digital number display.
Ébauche (or Blanc Roulant)
The main elements of a watch movement without its regulating organ, mainspring, dial or hands. This is often what is sold to watch manufacturers, when they will create their own additional parts.
Elapsed Time Rotating Bezel
A graduated rotating bezel that is used to keep track of periods of time. The bezel can be rotated so the wearer can align the zero of the bezel with the watch’s minutes or seconds hand. The elapsed time can then be read off the bezel, rather than the wearer having to perform a subtraction necessary if he used the watch’s regular dial.
Enamelling
Is a way to finish a dial by heat firing glass powder to a molten state and once it cools, it has a flat shine to it. Whilst some enamel can be a single colour, specialist artistic images can be created by using multiple enamelling methods. It is one of the oldest artistic and artisanal crafts still practiced in horology today and remains an incredibly specialist skill.
Engine Turning
A craft from hundreds of years ago, that now involves the use of antique machines to engrave delicate patterns on metal watch components, including cases, dials, bezels and movements, which is able to create a guilloché.
Equation of Time
A complication which shows the difference between the time as we usually know it and shown by a watch (24 hours, separated into hours, minutes and seconds) and solar time, which varies every day depending the Earth’s orbit on it’s axis.
Escapement
The device in a mechanical movement that controls the rotation wheels and therefore the hands.
Exhibition Caseback
A caseback which has a window of crystal, so the movement can be seen from the back of the watch.
Flange
The inner ring between the crystal and dial.
Flinqué
A dial decoration technique, where guilloche is given an enamel coating, to soften the look and often adding a visual enhancement.
Flyback (or Retour en Vol)
A seconds hand on some chronographs that can be reused immediately, after resetting the hands. Useful where time intervals need to be measured in quick succession.
Frequency
Frequency in watchmaking is measured by two different terms: Hertz (Hz) and vibrations per hour (VpH); they are interconnected.
Functions (or Complications)
The various different tasks a watch can perform other than timekeeping, such as chronograph and countdown timer.
Gas Escape Valve (or Helium Escape Valve)
Found on some dive watches, this has been developed to protect watches from damage which can potentially be caused by increasing pressure on ascent to the surface. The one way valve releases any gases trapped inside the watch case during decompression.
Gasket
A (usually) rubber seal, which protects the movement of a watch from things such as water, dust and any other particles that may enter the movement and cause issues.
Gear Train
The system of gears which transmits power from the mainspring of the watch to the escapement.
Geneva Stripes (or Côtes de Genève)
A traditional Swiss decoration on watch movements, made by intricately engraving tiny, angled scratches in a systematic manner onto the metal, to create what looks like parallel stripes.
Gilt Dial
A watch which has gold on the dial; not limited to, but could be highlights around the indexes, or perhaps lettering.
Glucydur
A hard and stable alloy (copper, beryllium and iron), that has been used to make balances since the 1930’s.
Gold plating
A layer of gold that is plated onto a base metal. The thickness of the plating is measured in microns (1000th of a mm).
Grand Complication
A watch with at least three functions, or complications, in addition to timekeeping.
Guilloché
An intricate decorative technique, where a repeated pattern is engraved on a flat surface.
Hacking Seconds (or Stop Seconds)
A watch where the seconds hand stops when the crown is pulled out (usually whilst changing the time).
Hand Wound (or Manual Wound)
A timepiece that has an inner movement that must be wound by the wearer on a regular basis, in order to keep it powered up. It is generally wound via the crown in a singular direction to wind the mainspring.
Haute Horlogerie
A French word meaning “high-art of watchmaking” and refers to the highest standard in watchmaking.
Hairspring (or Balance Spring)
A very fine spring in a mechanical watch that causes the recoil of the balance wheel. The length and adjustment of its length regulates the accuracy of the timekeeping.
Heat Blued
Certain parts of a watch, such as hands and screws are tempered at a high temperature, which was originally used to render them harder, however, now is a decorative method. Different temperatures used in tempering can produce other colours, such as purple and brown, but one of the most difficult is bright blue.
Helium Escape Valve (or Gas Escape Valve)
Found on some dive watches, this has been developed to protect watches from damage which can potentially be caused by increasing pressure on ascent to the surface. The one way valve releases any gases trapped inside the watch case during decompression.
Hertz
Is a measurement for the number of oscillations that a balance wheel makes each second.
Horology
The science of time measurement, which includes the art of designing and constructing watches.
Hour Marker
An indication on a dial that shows when hours occur.
Hybrid Watch
A traditional looking mechanical watch, but with “smart” functions, that can often be seen in a small area of the dial, or that maybe there is no evidence on the dial, but can be connected via Bluetooth to track specific information, such as steps and vital signs.
Indexes (or Indeces)
An hour indicator on an analogue watch dial; often used instead of numerals.
Inertia Block
A small piece of metal attached to the balance wheel, which is used to regulate variation (increase/decrease) the movement of the balance.
Integrated (or integral) Bracelet
A bracelet that is shaped and attached to the case of a watch in such a way that it appears to be part of the watch, with the lines of the case smoothly continuing into the bracelet and vice versa.
Jewels
Synthetic gemstones that act as bearings for the gear trains, helping to reduce friction and wear on parts.
Jumping Hour
A hand or other hour indication that shows one hour and “jumps” immediately to the next hour, as soon as the 60th minute of the current hour completes.
Jumping Seconds (or Dead Beat Seconds)
A mechanical movement with a hairspring and balance, whose second hand beats at 1Hz (or one beat a second), rather than appearing to smoothly move around the dial.
Karat
A a measurement indicating the proportion of gold in an alloy out of 24 parts, so for example, 18K gold is 18/24 parts gold.
Lever Escapement
Transmits energy from the mainspring via a train of wheels to the balance wheel, in order for it to oscillate. The impulse happens in both directions as the balance oscillates and between the impulses it locks the train, so that the mainspring unwinds at a constant and consistent rate.
Liga
A German acronym that stands for Lithographie (lithography), Galvanisierung (electroplating) and Abformung (plastic moulding), whereby perfect micro components can be “grown” out of Nickel in a plating bath. No trimming ,finishing or polishing is required after manufacture.
Liquid Crystal Display (LCD)
A numeric display where the liquid held in a thin layer between two transparent plates displays an image. In watches, numbers are made up from seven segments that form the number 8 when all are activated.
Lugs
The areas on a watch case where the strap or bracelet is attached to.
Lume
A substance painted on dials, hands and other parts of watches, to enable them to be seen/read in the dark.
Lumicast
Swiss made ceramic parts, which have a high luminous effect.
Luminous
To glow in the dark.
Magnetism
An issue that affects mechanical watches, where major components cannot interact as they normally would within the structure of the movement, due to magnetic force. It can cause fast/slow running and other erratic behaviour, as well as stopping altogether.
Main Plate
The (usually metal) base plate upon which all other parts of a watch movement are mounted.
Mainspring
The coiled spring which provides the power to drive a mechanical watch movement.
Manual Wound (or Hand Wound)
A timepiece that has an inner movement that must be wound by the wearer on a regular basis, in order to keep it powered up. It is generally wound via the crown in a singular direction to wind the mainspring.
Marine Chronometer
A highly accurate mechanical or electronic timekeeper that is enclosed in a box and is used for determining the longitude on board a ship. Marine chronometers with mechanical movements are mounted on gimbals so they are in the horizontal position that is essential for their precision.
Measurement Conversion
A feature that allows the wearer to convert one type of measurement into another. It usually consists of a graduated scale on the bezel or dial.
Mechanical Movement
The name for the traditional watch movement. A mechanical watch is driven by a slow release of power from a mainspring via a set of small cog wheels. The spring is wound up manually.
Micron
A thousandth of a millimeter and is a measurement used to measure the thickness of gold plating.
Mineral Crystal
Used in watch crystals, it costs more than acrylic but not as much as sapphire. Similar to the glass used in standard windows, it is a silica product that offers good scratch resistance and moderate durability. At a glance, it is quite difficult to tell the difference between mineral and sapphire.
Minute Repeater
An acoustic function on a watch that sound the time in hours, quarters or minutes. This is made up of hammers and gongs, to play either a single sound, or a melody.
Mirrored Force
The synchronisation of two balance wheels which are oscillating in opposite directions at the same time, the ultimate purpose being improved accuracy.
Monopusher Chronograph
A chronograph watch whish has only 1 single button (in addition to the crown) to control all functions.
Moonphase
A window in a watch, which indicates the phases of the moon through 29 ½ days. Some complicated moonphase watches incorporate an automatic correction for the extra 44 minutes per month throughout the year.
Mother of Pearl
The iridescent interior of a freshwater mollusc, that is often used to decorate watch dials. Its colours can include white, grey, blue and pink.
Movement
The motor of a watch, that allows it to keep time and perform functions.
Multi-functional
A watch that can perform different functions, such as a stopwatch or a countdown time, whilst still giving the correct time.
Nato Strap
A military style strap that is linked behind the case, but attaches separately to each of the watch’s lug bars for extra security, in case one of the bars pops out.
Numerals
Numbers shown on a watch dial.
Oscillating Weight (or Auto Rotor)
A component which is attached to the watch movement and connected to the mainspring by an intricate series of gears. As it swings and rotates with the wearer’s wrist movements, it winds the mainspring as it turns and ultimately feeds energy to make the watch function. It is usually a semi-circlular metal weight.
Oscillations
The return (back and forth) movement of an oscillating component, which is limited by two extreme positions, are measured by oscillations per second and depicted by Hz. 1 oscillation equates to 2 vibrations each second. 1 Hz = 3,600 vph/bph.
Passage au Sonnerie
An hourly chime as a watch reaches the new hour.
Patent
A protected and exclusive legal right to exclude others from making, using, or selling an invention for a limited period of time, in exchange for publishing an enabling disclosure of the invention.
Patina
A natural oxidisation that occurs on certain metals and other natural materials, which can create colour distortions and what appear to be imperfections over time.
Perlage
French for “pearl pattern”, and a type of decoration applied to movements, consisting of small, overlapping circles.
Perpetual Calendar
A watch that automatically takes into account variations in the length of the month and leap years, and alters the calendar accordingly, without any additional manual intervention.
Perpetual Movement (or Automatic/Self-winding)
Winding that occurs through movement of the wearer, rather than by turning the crown and winding stem. A component turns in response to motion, winding up the watch’s mainspring, creating power.
Perlon Strap
A strap made from perlon nylon, that is weaved into loops.
Plate
A platform (usually metal), which acts as main fixing masses for parts which make up the gear train and movement of a watch.
Platinum
Platinum is one of the rarest and most durable of precious metals. It doesn’t tarnish and has a radiant, beautiful white shine to it and a popular choice for luxury watches.
Power Reserve
The length of time a watch can run on its own once fully wound.
Power Reserve Indicator
A feature of some mechanical watches which indicates operating power time left; in other words, how much longer the watch will operate before it needs to be wound again.
Pulsometer
A scale on a chronograph which is used for measuring pulse rate.
Pushers
A button that can be pressed to operate a specific watch function (or functions), such as a chronograph, or alarm.
Qualité Fleurier
A quality certification that must fulfil certain criteria, including COSC certification, robustness and precision tests, exquisite finishing and being 100% Swiss Made.
Quartz Crystal
A slice of synthetic quartz crystal within a quartz movement watch. When an electric current is passed through the quartz it oscillates at the rate of 32.768 Hz, dividing time into equal segments and therefore regulating the time.
Quartz Movement
An electronic watch movement with a quartz crystal that oscillates when a current is applied to it. Power is normally provided by a battery or capacitor and it is often the case that they can be more accurate than mechanical movements.
Quick Set
The day, date, or other functions can be advanced quicker than by repeatedly rotating the hour hand through it’s 24 hour cycle.
Radial Dial
A dial where hour markers are heading more towards the centre and often spacing between the minute track and numerical markers are further apart.
Rattrapante (or Split Seconds)
This refers to two seconds hands – one of which can be stopped to indicate a time period, whilst the other continues to run. When restarted, the stationary seconds hand jumps to the position of the other seconds hand (which has now stopped) and continues to move past in order to keep the seconds timing constant This, in effect, splits the hand in two and allows the timing of different sections of a race (or other event) to be captured.
Reference
The watch manufacturer’s code for a specific model variance.
Regatta Timer (or Yacht Timer)
A countdown timer, which shows and/or sounds warning signals during the countdown to a water-based race.
Regulator
Displays minutes on the main dial; and hours and seconds on separate sub dials.
Rehaut (or Flange)
The inner ring between the crystal and dial.
Reserve de Marche (or Power Reserve Indicator)
A feature of some mechanical watches which indicates operating time left; in other words, how much longer the watch will operate before it needs to be wound again.
Resonance
Two independent escapements that are connected in a watch movement, that influence each other; the purpose being to average out any potential timing errors.
Retour en Vol (or Flyback)
A seconds hand on some chronographs that can be reused immediately, after resetting the hands. Useful where time intervals need to be measured in quick succession.
Retrograde Display
Displays time or date in a linear fashion and jumps back to the start once it reaches the end of the display.
Rhodium Plating
A top coating, usually over a base metal of gold, silver, or other alloy that is coated in a thin layer of rhodium for extra strength and luster. Often used on main plates and bridges, it is generally more durable than other metals and resistant to corrosion.
Roman-Arabic Dial (or Californian Dial)
When Roman numerals and Arabic numerals can be found on the same dial.
Rotating Bezel
A bezel that can be rotated in one or 2 directions, depending on it’s use.
Rotor
The oscillating part of a self-winding watch that winds the mainspring.
Roulette Date
The date numerals are shown in alternating colours of black and red.
Sapphire Case
A watch case that is made entirely from sapphire crystal (usually synthetic).
Sapphire Crystal
The cover that protects the watch dial, usually made of synthetic sapphire, which is a transparent, scratch resistant substance.
Satellite Hour
A display that shows the hour as it travels around the dial. This is usually via a small sub dial, or a window, both of which usually travel with the minute hand or display.
Screw Balance
A sign of a quality movement, which is achieved by adding weights (in the form of screws) to the balance, in order to achieve the perfect impetus.
Screw Down Crown
A crown which screws down and nestles into a threaded barrel, which ultimately aids water resistance.
Seal of Geneva
An award reserved for Genevan watch manufacturers that conform to specific standards of finishing. Testing is done on the finished watch and consitest of one on the movement and one on the case.
Second Time Zone Indicator
An additional dial that can be set to indicate the time, in another time zone. This allows the watch to display the time in two time zones simultaneously.
Self-winding (or Automatic Winding/Perpetual)
Winding that occurs through movement of the wearer, rather than by turning the crown and winding stem. A component turns in response to motion, winding up the watch’s mainspring, creating power.
Serial Number
The identification number of a watch, usually engraved on the case or movement. This can be used to gauge authenticity and trace history.
Shock Absorber
A resilient part, which takes up the shocks received by the watch’s movement and protects other areas from damage.
Shock Resistance
The ability to withstand an impact equal to that of being dropped onto a solid floor from a height of 3 feet.
Silicium (or Silicon)
Relatively new to mechanical watches and currently being used in the manufacture of precision escapements. They often require less, or even no lubrication and have a long life.
Skeleton Watch
A watch case with a transparent front, back, or both, which allows visibility of the watch’s movement.
Slide Rule
A device consisting of a scale on the outer edge of a watch dial (or bezel) which enables mathematical calculations.
Smart Watch
A portable device that is designed to be worn on a wrist. Many are like smartphones, which use touchscreens and have useful applications such as calculators, mobile connectivity and monitoring of heart rate and other vital signs. Some are less interactive, however, still have a degree of technology in order achieve certain functionality.
Solar Powered Battery
A battery (or batteries) in a quartz watch, that are recharged via solar panels on the watch dial.
Sports Watch
A type of tool watch that has a use whilst taking part in a sport. This may be a function or complication, but could also be named such purely by its appearance.
Split Seconds (or Rattrapante)
This refers to two seconds hands – one of which can be stopped to indicate a time period, whilst the other continues to run. When restarted, the stationary seconds hand jumps to the position of the other seconds hand (which has now stopped) and continues to move past in order to keep the seconds timing constant This, in effect, splits the hand in two and allows the timing of different sections of a race (or other event) to be captured.
Spring Barrel
A cylindrical metal box, which is closed by a cover and has a ring of gear teeth around it. A spiral spring called the mainspring is contained within this, which provides power to run the movement once it has been wound.
Stainless steel
A durable metal alloy that is almost rust resistant and rarely corrodes or discolours, that is used regularly in watch cases and bracelets. It is also sometimes used on the case backs of watches made of other materials.
Stop Seconds (or Hacking Seconds)
Stopwatch
A watch with a seconds hand, that measures elapsed time. When a stopwatch is incorporated into a watch, it is called a chronograph.
Stepping Motor
The part of a quartz (analogue) movement, that moves the gear train, which in turn moves the hands around the dial.
Sterling Silver
A highly reflective precious metal, which is 92.5% pure and is often used to make watch cases and other parts.
Subsidiary Dial
A small dial on a watch face, which can be used for a multitude of purposes, such as keeping track of elapsed time, seconds, date etc.
Sunburst Dial
A radiant finish, created by scoring ultra-thin lines (usually made by a wire wheel) which emanate from the centre and then coating with the dial’s final colour. It has a subtle texture and appears to change depending on the light.
Sunburst Guilloché
A hand turned design which radiates out from a centre point (often the centre of the dial where the hands are affixed), to create an effect similar to the rays of the sun bursting out.
Super Luminova
Swiss made Super–LumiNova® is non-radioactive substance for illuminating markings on watch dials, hands and bezels. Charged by light, but used to see the watch markings in the dark and/or under water.
Swan Neck
A part used to regulate the speed of a movement, by making fine adjustments to the length of spring – the shorter the length of spring, the faster the motion of balance wheel and conversely, the longer the length of spring, the slower the balance wheel’s motion.
Sweeping Seconds
A centrally mounted seconds hand that moves around the dial of a watch, without a noticeable “ticking”. Often seen in mechanical self-winding watches.
Swiss Made
A watch can only be said to be Swiss Made if the movement was assembled, started, adjusted and controlled by a manufacturer in Switzerland.
Swiss A.O.S.C.
A certificate of origin – a mark which identifies a watch that has been assembled in Switzerland and has components of Swiss origin.
Tachymeter
A scale used for measuring speed, usually in chronographs. used in conjunction with the seconds hand, a set of markings on the outside of a watch measures the wearer’s speed over a known distance.
Telemeter
A scale used for measuring distances, mostly in connection with chronographs. A distance can be measured due to a visible and audible event. The markings on the dial are based on the speed of sound in air (340 meters per second). An example of use would be during a thunderstorm – when you see the flash, start the hands and stop it when you hear the thunder. The hand tells you how far away the storm is.
Thirty Minute Counter
A subsidiary dial on a chronograph, that can time periods of up to 30 minutes.
Timer
A device for registering intervals of time, without showing any indication of the time of day.
Titanium
A metal with a silvery appearance that is stronger and lighter than steel. Titanium is commonly used in watchmaking, as it is hardwearing and resistant to corrosion.
Tonneau
A tonneau watch is shaped like a barrel with two convex sides and curved to follow the shape of the wrist.
Tool Watch
A watch that was originally designed to help complete a specific task. For example, a diving watch has an bezel to indicate available air by time elapsed and water resistance.
Totaliser
A mechanism that keeps track of and displays elapsed time; usually stop-watch intervals and often on a subsidiary dial.
Tourbillon
A device that eliminates timekeeping errors caused by small differences in the how a watch runs in the vertical and horizontal positions. It consists of a round cage, holding the balance and escapement. It generally rotates continuously at the rate of one rotation per minute, however, there are instances where a full rotation can be either more or less than 60 seconds.
Tritium
An isotope of hydrogen that is painted on surfaces to make watch hands and indices glow in the dark. Tritium is mildly radioactive and feared by some to be a health hazard, so tritium paint is no longer used on dials.
Tropical Dial
A dial that has discoloured due to sustained exposure to the sun, usually combined with minor flaws in the manufacturing process.
Two-tone
A watch which uses two different types of metal in the case, bezel and/or bracelet. A typical example would be a stainless steel and gold.
Uni-directional Rotating Bezel
A bezel that can be rotated in one direction only and is used to monitor elapsed time (during diving). A ratchet mechanism is usually in place to prevent the bezel from inadvertently rotating in the other direction. It’s main function is to prevent a diver from running out of air by overestimating his or her remaining air supply. If the bezel moves in one direction only, it means the diver can only underestimate their remaining air supply (if the bezel is accidentally knocked off its position).
Vibrations
The single movement of an oscillating component, which is limited by two extreme positions, are measured by vibrations per hour (vph) or beats per hour (bph). 2 vibrations equate to 1 single oscillation. 3,600 vph/bph = 1Hz.
Wandering hour
Indicates the time by moving an hour display along a track or scale (often an arc), which points to the minutes.
Water resistance
The ability of a watch to withstand water pressures to various degrees.
Winding
To tighten the mainspring of a watch – it can be done manually, by turning the crown, or automatically, via a rotor weight, which is made to swing and rotate by the movement of the wearer’s wrist.
Winding Stem (or Crown)
The grooved button on the outside of the case, used for setting the hands on a watch, and the day and date, where applicable. It is also used for winding the mainspring of a mechanical watch.
World Time Dial
A dial that indicates the time of up to 24 time zones around the world. Names of specific cities are indicated on the dial and the hour in a particular zone, can be read by looking at the scale next to the city that the hour hand is pointing to. Minutes are read in the usual way.
World Timer
A watch that utilises a world time dial.
Yacht Timer (or Regatta Timer)
A countdown timer, which shows and/or sounds warning signals during the countdown to a water-based race.
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