Watch Mechanism Glossary: Movement and Complication Terms Explained

A

Anglage

The hand-beveled, polished edge applied to the flanks of a movement’s bridges and plates. On a high-end movement the angle is cut and polished by hand rather than stamped, which is why it remains a benchmark test in haute horlogerie finishing.

Annual calendar

A calendar complication that tracks the date, day and month while accounting for 30- and 31-day months automatically, requiring a manual correction only at the end of February. It sits a tier below a perpetual calendar in complexity and price, since it does not track leap years.

Anti-magnetic

A movement built to resist the timing errors caused by exposure to magnetic fields, typically through non-ferrous components such as a silicon hairspring or a soft-iron inner case. Several manufactures market entire calibre families on this property alone.

Anti-reflective coating

A thin coating applied to one or both sides of the sapphire crystal to reduce glare and improve dial legibility. Some manufacturers coat only the underside, keeping the visible top surface harder and more scratch-resistant.

Assembly

The process of fitting a movement’s components together, split between machine assembly for high-volume calibres and hand assembly for complications or haute horlogerie pieces. A watchmaker at manufacture level typically assembles, regulates and disassembles a single movement more than once before casing.

Automatic movement

A mechanical movement wound by the natural motion of the wearer’s wrist, using an oscillating rotor connected to the mainspring through the gear train. It differs from a manual movement only in how the mainspring is wound, not in how the going train or escapement function.

B

Balance wheel

The oscillating wheel that, together with the hairspring, regulates the rate at which a mechanical movement runs. It swings at a fixed frequency, and any adjustment to its poise directly affects a watch’s accuracy.

Barrel

The cylindrical container that houses the mainspring and releases its stored energy through the gear train to the escapement. A movement’s power reserve is a direct function of the barrel’s size and the mainspring’s length.

Beat rate

The frequency at which a movement’s balance wheel oscillates, usually expressed in vibrations per hour or Hertz. A higher beat rate generally produces a smoother sweeping seconds hand, though it also increases wear on the escapement over time.

Bezel

The ring surrounding the crystal, fixed or rotating, finished in materials from steel to ceramic to sapphire. On dive and GMT watches it is typically functional, tracking elapsed time or a second time zone, while on dress watches it is usually decorative.

Big date

A date display enlarged well beyond a standard single-digit window, usually achieved with two discs rather than one. High-complication manufactures popularised the format, and it remains associated with that tier more than mass-market date windows.

Bridge

A metal plate that holds a movement’s gears and wheels in place from above, anchored to the mainplate. On an openworked or skeleton movement, the visible bridges are usually where a manufacture concentrates its hand-finishing.

Brilliant cut

The most common diamond and gemstone cut used in watchmaking, with 57 or 58 facets arranged to maximise light return. It appears throughout the industry on bezels, dials and bracelets, from entry-level pavé to the rarest high-jewellery pieces.

Brushed finish

A matte surface texture created by drawing fine, parallel lines into a metal case or bracelet, usually with abrasive belts or wheels. It is common on case flanks and bracelet centre links, often paired with polished bevels for contrast.

C

Calibre

A calibre is the specific model of movement inside a watch, identified by a name or reference number unique to its manufacturer. Two watches can share the same case and dial design yet run entirely different calibres, which is often the detail that separates an entry-level reference from a haute horlogerie one.

Case

The case is the metal housing that protects a watch’s movement, dial and crystal from dust, moisture and impact. Its construction, whether a simple two-piece design or a complex multi-part assembly, determines the watch’s water resistance and largely dictates its overall silhouette.

Case back

The case back is the panel that closes a watch case from behind, either solid or fitted with a sapphire window that exposes the movement. An exhibition case back is common on watches where the manufacture wants to showcase hand-finishing, while dive watches typically favour a solid back for maximum water resistance.

Case diameter

Case diameter is the width of a watch case measured across its middle, excluding the crown, and remains the most commonly cited dimension when comparing references. It does not by itself indicate how a watch wears on the wrist, which depends just as much on lug-to-lug length and case thickness.

Case middle

The case middle is the central body of the case that houses the movement, sitting between the case back and the bezel or crystal. Lugs, the crown tube and the case’s water-resistance gaskets are all integrated into or attached to this component.

Case stretch

Case stretch describes the gradual widening of a case’s lug holes from decades of pin or screw movement, a wear pattern collectors look for when assessing a vintage watch’s originality. Pronounced stretch can indicate a well-worn example or a case that has been serviced or polished repeatedly over its life.

Case thickness

Case thickness is the height of a watch case measured from the case back to the top of the crystal, a figure that grows with movement complexity and water-resistance rating. A slim dress watch may measure under 8mm, while a professional dive watch commonly exceeds 12mm.

Chamfer

A chamfer is a beveled edge cut into a movement component, most often a bridge, to soften a sharp corner and catch light. Hand-chamfering, where the angle is filed and polished individually rather than machine-stamped, is one of the clearest visual signs of high-end finishing.

Chronergy escapement

The Chronergy escapement is Rolex’s proprietary lever escapement, built from nickel-phosphorus components in a skeletonized architecture designed to improve energy efficiency over a traditional Swiss lever escapement. Its non-ferrous construction also makes it inherently resistant to magnetic interference.

Chronograph

A chronograph is a watch fitted with a stopwatch function, controlled by pushers that start, stop and reset an independent set of hands. It remains one of the most common complications in the industry, ranging from simple two-pusher designs to split-seconds and flyback variants.

Clous de Paris

Clous de Paris is a decorative pattern of small pyramid-shaped studs cut into a metal surface, most often seen on bezels, crowns and dial elements. The technique originated in French decorative arts before being adopted into watchmaking as a hallmark of traditional hand-guilloché work.

Clutch system

The clutch system is the mechanism that engages a chronograph’s stopwatch function with the running movement, built either as a horizontal design using a pivoting gear or a vertical design using stacked friction discs. A vertical clutch generally eliminates the small jump in the seconds hand that can occur with a horizontal clutch at the moment of engagement.

CNC machining

CNC machining is the computer-controlled cutting and shaping of movement and case components from raw metal stock, used throughout the industry for everything from mainplates to case bodies. It provides the dimensional precision required before parts move on to hand-finishing.

Column wheel

A column wheel is a toothed, upright wheel that coordinates the start, stop and reset functions of a chronograph, distributing commands to the mechanism’s levers in a fixed sequence. It is more complex and costly to produce than a cam-based switching mechanism, which is why manufactures often highlight its visible operation through an exhibition case back.

Complication

A complication is any function a watch performs beyond the basic display of hours, minutes and seconds, from a simple date window to a minute repeater or perpetual calendar. The more complications a movement combines, and the more precisely they interact, the more mechanically and commercially significant the watch is considered.

COSC certification

COSC certification is issued by the Contrôle Officiel Suisse des Chronomètres, the independent Swiss body that tests movements for accuracy before they are cased. A movement must meet a defined daily-rate tolerance across multiple positions and temperatures over a set testing period to earn the designation “chronometer.”

Côtes de Genève

Côtes de Genève, or Geneva stripes, is a decorative pattern of parallel wave-like lines applied to a movement’s bridges and mainplate. Despite the name, the technique is used by manufactures across Switzerland and beyond, and today is often applied by machine rather than by hand.

Crown

The crown is the knob on the side of a case used to wind the mainspring, set the time and, on many models, adjust the date. Screw-down crowns thread into the case tube to seal against moisture, and are standard on dive and sports watches.

Crown guards

Crown guards are raised shoulders built into the case on either side of the crown to shield it from knocks and accidental impact. They became closely associated with tool watches in the mid-20th century and remain a common feature on dive and pilot watch designs.

Crystal

The crystal is the transparent cover that protects a watch’s dial, most commonly made from sapphire for its scratch resistance or, on vintage pieces, acrylic for its shatter resistance. Sapphire crystal is now the industry standard above the entry-level price tier, often finished with a domed profile or an anti-reflective coating.

Cyclops lens

The Cyclops lens is a small magnifying bubble set into the crystal over the date window, most closely associated with Rolex, which introduced it in the 1950s. It magnifies the date to improve legibility at a glance.

D

Date

The date function displays the calendar day, either through a small window on the dial or, less commonly, with a hand pointing to a printed scale. It is the simplest and most widely fitted calendar complication in the industry.

Day-date

A day-date complication displays both the calendar day and the full name of the weekday, usually through two separate windows or apertures on the dial. It typically requires a quickset mechanism to allow both indications to be advanced independently of the main timekeeping.

Depth rating

Depth rating is the maximum water pressure a case is certified to withstand, usually expressed in metres or bar and tested with a safety margin beyond the stated figure. A depth rating does not mean a watch is intended for diving to that exact depth, since the number reflects a laboratory pressure test rather than a real-world dive limit.

Dual time

A dual time watch displays two time zones simultaneously, typically through a secondary hand, subdial or rotating disc that runs independently of the main hour and minute hands. It differs from a GMT complication mainly in mechanism and display, though the two terms are often used loosely to mean the same thing.

E

Ébauche

An ébauche is an unfinished movement blank, supplied with its basic going train and plates assembled but lacking the escapement, finishing and regulation needed to run. Historically, smaller Swiss manufactures relied on outside ébauche suppliers to build finished movements around a shared base.

Enamel

Enamel is powdered glass fused to a metal surface at high temperature, used in watchmaking for dials, caseback medallions and decorative panels. Grand feu enamel, meaning “great fire,” refers to the traditional multi-firing technique that produces the deepest colour and the most durable finish, though it also carries the highest risk of cracking during firing.

Engraving

Engraving is the technique of cutting a design directly into a metal surface with a sharp tool, used on watches for everything from case backs to decorative motifs on bridges. Hand engraving, where a craftsman guides the tool freehand rather than relying on a machine, remains one of the most time-intensive forms of watch decoration.

Escape wheel

The escape wheel is the toothed wheel at the heart of the escapement that releases the mainspring’s energy in small, regular increments, governed by the pallet fork. Its interaction with the pallet fork is what converts continuous rotational energy into the ticking motion of a mechanical watch.

Escapement

The escapement is the mechanism that regulates the release of energy from the mainspring to the balance wheel, converting it into the fixed, measurable beats that allow a mechanical watch to keep time. The Swiss lever escapement has dominated the industry since the 19th century, though several manufactures have introduced proprietary alternatives designed to improve efficiency or resist magnetism.

Everose gold

Everose gold is Rolex’s proprietary pink gold alloy, developed in-house to resist the fading that affects many rose gold formulations over time. It is produced at Rolex’s own foundry and used exclusively across the brand’s rose gold models.

F

Finishing

Finishing refers to the decorative and functional treatments applied to a movement’s components after machining, from beveled edges to polished screw heads and striped bridges. The extent and quality of a movement’s finishing, and whether it is done by hand or machine, is one of the primary ways collectors judge a manufacture’s craftsmanship.

Flyback chronograph

A flyback chronograph allows the stopwatch function to be reset and restarted instantly with a single push of the pusher, rather than requiring separate stop, reset and start actions. The complication originated for aviation use, where pilots needed to time successive intervals without losing a beat between them.

Frequency

Frequency is the rate at which a movement’s balance wheel oscillates, expressed in Hertz, and is mathematically linked to the beat rate expressed in vibrations per hour. A higher frequency generally improves a chronograph’s timing resolution and produces a smoother sweep of the seconds hand, at the cost of greater wear on the escapement.

G

Gear train

The gear train is the series of interlocking wheels that transmits energy from the mainspring barrel through the movement to the escapement. Its gearing ratios determine how the movement’s various hands are driven at their correct relative speeds.

Ghost bezel

A ghost bezel refers to a bezel insert, typically matte black, whose printed or applied markings have faded or discoloured evenly through age and UV exposure rather than wear. The look has become desirable among collectors of vintage tool watches, distinct from the colour shift seen on an aged dial.

GMT

GMT refers to a complication that displays a second, and sometimes third, time zone using an independent 24-hour hand and a rotating or fixed bezel marked with a corresponding scale. The name derives from Greenwich Mean Time, the reference point the complication was originally designed around for pilots and international travellers.

Grand feu enamel

Grand feu enamel is the traditional high-temperature enamelling technique in which layers of powdered glass are fired repeatedly in a kiln, each firing building depth and permanence into the colour. It is considered the most demanding and prestigious form of enamel work, with a meaningful failure rate during production due to the risk of cracking at high heat.

Guilloché

Guilloché is a decorative technique in which a repeating geometric pattern is engraved into a metal surface using a manually operated rose engine or straight-line engine. Traditional hand-guilloché is increasingly rare, with most modern watches using CNC-engraved patterns that mimic the historical technique.

Gyromax balance

The Gyromax balance is Patek Philippe’s proprietary variable-inertia balance wheel, fitted with small adjustable weights around its rim that let a watchmaker fine-tune the movement’s rate without altering the hairspring itself. The design allows for finer poising and regulation than a traditional balance with a separate regulator index.

H

Hacking seconds

Hacking seconds is a mechanism that stops the seconds hand the moment the crown is pulled out to set the time, allowing the watch to be synchronised to the exact second against a reference clock. It became a standard expectation on tool watches after being required for military-issue timepieces in the mid-20th century.

Hairspring

The hairspring is the fine coiled spring attached to the balance wheel that causes it to oscillate at a regular rate, acting as the movement’s timekeeping regulator alongside the balance itself. Its material and geometry have a greater influence on a watch’s accuracy than almost any other single component, which is why several manufactures have developed proprietary silicon or alloy hairsprings to reduce sensitivity to temperature, magnetism and shock.

Hand-finishing

Hand-finishing refers to any decorative or functional treatment on a movement performed manually rather than by machine, from beveling and polishing to engraving and anglage. It is significantly more time-consuming and expensive than machine finishing, and remains one of the clearest markers separating haute horlogerie movements from industrially produced ones.

Helium escape valve

A helium escape valve is a one-way valve fitted to some professional dive watches that releases helium gas which has built up inside the case during saturation diving, preventing the crystal from popping off during decompression. It is a feature relevant almost exclusively to commercial saturation divers rather than recreational ones.

Home time

Home time is a secondary time display, usually shown via a 24-hour hand or subdial, that keeps track of a wearer’s home time zone while the main hands are set to local time while travelling. It serves the opposite function to a standard GMT hand, which is typically set to track a second time zone away from home.

I

In-house movement

An in-house movement is one designed, manufactured and assembled entirely within a single brand’s own facilities, as opposed to a third-party movement sourced from an outside supplier and modified. The distinction has become a significant marketing and pricing factor, though it says more about a brand’s manufacturing independence than it does about a movement’s actual quality or performance.

J

Jewels

Jewels are small synthetic rubies or sapphires set at friction points throughout a movement, such as pivots and pallet stones, to reduce metal-on-metal wear and friction. The number of jewels varies by design and complication count and is not by itself a reliable measure of a movement’s quality.

L

Leap year indicator

A leap year indicator is a small display, typically fitted to a perpetual calendar, that tracks where the movement is within the four-year leap year cycle. It confirms that the mechanism will correctly account for the extra day in February without manual intervention.

Lubrication points

Lubrication points are the specific locations within a movement, such as pivots, the escapement and the mainspring barrel, where oil or grease is applied during assembly to reduce friction and wear. The type and viscosity of lubricant used at each point is chosen for that component’s specific speed and load, and degrading lubrication is one of the main reasons a mechanical watch requires periodic servicing.

Lug

A lug is one of the projections extending from the case that holds the strap or bracelet in place via spring bars. Most watches have two lugs at each end of the case, and their width directly determines which strap or bracelet sizes will fit.

Lug-to-lug

Lug-to-lug is the total length of a case measured from the tip of the top lugs to the tip of the bottom lugs, a figure that has a greater practical effect on how a watch fits a wrist than case diameter alone. Two watches with an identical diameter can wear very differently if their lug-to-lug measurements differ significantly.

M

Mainplate

The mainplate is the primary structural plate of a movement, onto which the gear train, barrel and other components are mounted and around which the bridges are fitted. It forms the foundation that every other part of the movement is built upon.

Mainspring

The mainspring is the coiled metal spring housed inside the barrel that stores the energy used to power a mechanical movement, wound either manually or by an automatic rotor. Its length and material directly determine how long a movement can run before it needs winding again.

Manual movement

A manual movement, also called hand-wound, requires the wearer to wind the crown periodically to keep the mainspring under tension and the watch running. It lacks a rotor, which typically allows for a slimmer case than an equivalent automatic movement.

Manufacture

A manufacture is a watch brand that designs and produces its own movements in-house, as opposed to a brand that assembles watches around movements bought from outside suppliers. The term is used loosely across the industry, and a brand can be a manufacture for some calibres while still sourcing others externally.

Matte finish

A matte finish is a surface treatment that scatters light evenly to produce a non-reflective, flat appearance, commonly used on dials, cases and movement components as a contrast to polished or brushed surfaces. It is achieved through sandblasting, bead blasting or specific chemical treatments depending on the material.

Microstella nuts

Microstella nuts are small gold weights set into the rim of Rolex’s balance wheel, used by watchmakers to fine-tune poise and rate without adjusting the hairspring. They serve the same basic regulating function as timing screws on other manufactures’ balance wheels, under Rolex’s own proprietary naming.

Milling

Milling is a machining process that uses a rotating cutting tool to remove material from a solid block, shaping components such as case bodies, bridges and mainplates to precise tolerances. It is typically the first stage of production before parts move on to finishing and decoration.

Monobloc case

A monobloc case is constructed as a single, sealed unit accessed only through the front, with the movement installed through the crystal opening rather than through a removable case back. Rolex uses the design across its Oyster case family, where it contributes to the case’s water resistance by minimising the number of joints and seals.

Moonphase

A moonphase complication displays the current phase of the moon, typically through a rotating disc printed with two moons visible through an aperture on the dial. A standard moonphase mechanism drifts gradually from the true lunar cycle over time, while more advanced versions are engineered to hold their accuracy for considerably longer before needing correction.

Movement

The movement is the mechanical or electronic engine inside a watch that measures the passage of time and drives its hands and complications. Movements are broadly divided into mechanical types, whether manual or automatic, and quartz types powered by a battery and oscillating crystal.

O

Oyster case

The Oyster case is Rolex’s trademarked waterproof case design, introduced in 1926 as one of the first commercially successful water-resistant watch cases. Its sealed, screw-down construction, combining the case back, crystal and crown, became the foundation for every subsequent Rolex sports model.

Oystersteel

Oystersteel is Rolex’s proprietary name for the 904L stainless steel alloy it uses across its steel case and bracelet production. The alloy offers greater resistance to corrosion than the more commonly used 316L steel, at the cost of being more difficult to machine.

P

Pallet fork

The pallet fork is the component that interacts with the escape wheel, alternately locking and releasing it to regulate the flow of energy through the escapement. Its rocking motion, driven by the balance wheel, is what produces the audible ticking of a mechanical movement.

Parachrom hairspring

The Parachrom hairspring is Rolex’s proprietary hairspring, made from a niobium-zirconium alloy rather than the traditional steel alloys used industry-wide. Its non-ferrous composition makes it resistant to magnetic fields, and it is treated with a blue oxide coating that gives it its distinctive colour.

Paraflex shock absorber

The Paraflex shock absorber is Rolex’s proprietary shock-protection system for the balance wheel, designed to improve resistance to impact compared with a standard shock-absorption system. It performs the same basic role as other brands’ shock-protection systems, such as Incabloc, cushioning the delicate balance staff against sudden jolts.

Patek Philippe Seal

The Patek Philippe Seal is the manufacture’s in-house quality and precision standard, introduced in 2009 to replace its long-standing use of the Geneva Seal. It certifies both the construction quality of the movement and the timekeeping precision of the fully cased and finished watch.

Perlage

Perlage is a decorative finish of small overlapping circular patterns applied to a movement’s mainplate or bridges, traditionally created by hand using a rotating abrasive tool. It originated partly as a practical way to disguise minor tooling marks left on a plate’s surface, and has since become a decorative standard in its own right.

Perpetual calendar

A perpetual calendar is a calendar complication that automatically accounts for the varying lengths of months, including the leap year cycle, without requiring manual correction for decades at a stretch. It is generally regarded as one of the more complex and prestigious complications a manufacture can produce.

Platinum

Platinum is a dense, naturally white precious metal used in the highest tier of watch cases and bracelets, prized for its rarity and resistance to tarnish. It is significantly heavier than gold of the same volume, which gives platinum watches a distinctive weight on the wrist, and it is generally the most expensive case material a brand offers.

Pointer date

A pointer date is a date display in which a dedicated hand sweeps around a printed numerical scale on the dial’s outer edge, rather than showing the date through a small window. It requires a full 31-day rotation of the dedicated hand and is generally considered a more elegant, though less space-efficient, alternative to a date window.

Polished finish

A polished finish is a mirror-bright surface treatment achieved by progressively buffing a metal surface with finer and finer abrasives until it reflects light with no visible texture. It is commonly applied to bevels, case flanks and bracelet centre links, often in contrast with a brushed or satin surrounding finish.

Power reserve

Power reserve is the length of time a fully wound mechanical movement will continue running before it stops, determined primarily by the length of the mainspring and the movement’s rate of energy consumption. Standard movements typically offer several days or less, while specialised calibres have been developed with reserves extending considerably further.

Pushers

Pushers are the buttons on a case, most commonly associated with chronographs, used to start, stop and reset the stopwatch function. Screw-down pushers, which thread into the case for extra water resistance, are common on dive chronographs where sealing against water ingress takes priority over quick operation.

PVD coating

PVD, or physical vapor deposition, is a coating process in which a thin layer of metal is vaporised in a vacuum chamber and deposited onto a case or bracelet surface, most often to produce black or coloured finishes. It is more durable than simple plating, though it can still wear through to the base metal at points of repeated contact over time.

Q

Quartz movement

A quartz movement uses a battery to send an electrical current through a synthetic quartz crystal, which oscillates at a precise, fixed frequency to regulate an electronic stepping motor that drives the hands. It is inherently more accurate than a mechanical movement and requires no winding, though it lacks the mechanical complexity that many collectors value.

Quickset date

Quickset date is a mechanism that allows the date to be advanced directly via the crown, independently of moving the main hands forward through a full 24-hour cycle. Its absence on some vintage and entry-level movements means the only way to correct the date is to cycle the hands repeatedly past midnight.

R

Rattrapante

Rattrapante is the French term for a split-seconds chronograph, a complication that uses two overlapping seconds hands to time two events that start together but end separately. One hand can be stopped independently to read an intermediate time while the second hand continues running, then released to instantly catch up with it.

Regulation

Regulation is the process of adjusting a movement’s rate so that it keeps time as close to perfectly as possible, carried out by a watchmaker using a timing machine to measure performance across multiple positions. It is one of the final steps before a movement is cased, and is typically repeated whenever a watch is serviced.

Regulator

A regulator is the component, or index, that fine-tunes the effective length of the hairspring and therefore the rate at which the balance wheel oscillates. Adjusting it slightly forward or backward speeds up or slows down the movement without requiring any other part to be altered.

Rehaut

The rehaut is the inner flange of a case that sits between the dial and the crystal, sometimes left plain and sometimes engraved with a serial number, model reference or decorative minute track. Engraved rehauts became more common industry-wide from the early 2000s onward as an additional anti-counterfeiting measure.

Remontage

Remontage is the French term for winding a movement’s mainspring, whether by hand via the crown or automatically through the motion of a rotor. The word appears throughout French-language watchmaking literature and in some manufactures’ own model naming.

Réserve de marche

Réserve de marche is the French term for power reserve, referring to the length of time a fully wound movement will continue to run before stopping. Several manufactures display this reading directly on the dial through a dedicated power-reserve indicator.

Reset hammer

The reset hammer is the component in a chronograph that snaps the stopwatch hands back to their zero position when the reset pusher is pressed. Its action must be precisely timed against the clutch and column wheel to avoid damaging the mechanism if the reset is triggered while the chronograph is still running.

Rolesor

Rolesor is Rolex’s proprietary term for its two-tone watches, which combine Oystersteel with either yellow, white or Everose gold across the case and bracelet. The name is a portmanteau of “Rolex” and “or,” the French word for gold.

Rose gold

Rose gold is a gold alloy that gets its warm pink tone from a higher proportion of copper mixed into the base gold, with the exact shade varying by manufacturer depending on the alloy’s precise composition. Several brands have developed their own proprietary rose gold formulations specifically to resist the colour fading that can affect standard alloys over years of wear.

Rotor

The rotor, or oscillating weight, is the semicircular or circular weight inside an automatic movement that swings freely with the wearer’s wrist motion, winding the mainspring through a series of gears. Rolex refers to its own rotor as the “Perpetual rotor,” a naming choice tied to its Oyster Perpetual model line rather than a fundamentally different mechanism.

S

Satin finish

A satin finish is a fine, directional surface texture that sits between a matte and a polished finish, produced by brushing a metal surface with an abrasive in a consistent direction under controlled pressure. It is widely used on case tops and bracelet outer links for a soft, low-glare sheen.

Shock absorber

A shock absorber is a spring-loaded component that cushions the balance wheel’s delicate pivots against sudden impacts, preventing the staff from breaking if the watch is dropped or knocked. Most modern movements use some variation of this system, whether a manufacturer’s own proprietary design or a widely licensed system such as Incabloc.

Silicon component

A silicon component is any movement part, most commonly a hairspring, escape wheel or pallet fork, manufactured from silicon rather than traditional metal alloys. Silicon is naturally resistant to magnetism, does not require lubrication, and can be produced with extremely precise, complex geometries using photolithographic manufacturing techniques.

Skeleton movement

A skeleton, or openworked, movement has its bridges and mainplate cut away as much as structurally possible to expose the gear train and escapement underneath. The technique transforms functional engineering into a visual display, and the quality of finishing on the newly exposed edges becomes just as important as the finishing on a traditional closed movement.

Sonnerie

Sonnerie is the French term for a striking mechanism that chimes the time on demand or automatically at set intervals, using hammers striking gongs coiled around the movement. A grande sonnerie chimes the hours and quarters automatically as time passes, while a petite sonnerie chimes only the hours automatically, with quarters available on demand.

Spiromax

Spiromax is Patek Philippe’s proprietary flat hairspring, made from Silinvar, a silicon-based material, and engineered with a specially shaped terminal curve that allows it to breathe concentrically without the raised overcoil a traditional flat hairspring requires. The design improves rate stability across different positions compared with a standard flat hairspring.

Split-seconds chronograph

A split-seconds chronograph, or rattrapante, uses two stacked seconds hands to time two events with different durations that start at the same moment. Pressing a dedicated split pusher stops one hand for an intermediate reading while the other continues running, and pressing it again releases the stopped hand to snap forward and rejoin its twin.

Stainless steel

Stainless steel is an iron-based alloy containing chromium, which gives it strong resistance to corrosion and staining, making it the most widely used case and bracelet material in the industry. The specific grade used varies by manufacturer, with 316L being the industry standard and several brands developing proprietary variants for greater hardness or corrosion resistance.

Sunburst finish

A sunburst finish is a radial brushed texture that emanates outward from a central point, catching and scattering light differently depending on the viewing angle. Though most closely associated with dials, the same technique is occasionally applied to case and bracelet components as a decorative accent.

Superlative Chronometer

Superlative Chronometer is Rolex’s own certification, applied after standard COSC testing, in which the fully assembled and cased watch is retested to a tighter daily-accuracy tolerance than COSC requires of the movement alone. Rolex introduced the designation in 2015 and displays it on the dial of every model that carries it.

Swiss lever escapement

The Swiss lever escapement is the most widely used escapement design in mechanical watchmaking, in which a pallet fork alternately locks and releases the escape wheel to regulate energy flow to the balance wheel. Developed in the 18th century, its combination of reliability and relative efficiency has kept it the industry standard even as manufactures continue to develop proprietary alternatives.

T

Tachymeter

A tachymeter is a scale, usually printed on a bezel or around a dial’s outer edge, that converts elapsed time over a known distance into a speed reading. It is used in conjunction with a chronograph’s stopwatch function, most commonly to calculate average speed over a fixed distance such as one mile or one kilometre.

Tapisserie

Tapisserie is a waffle-like decorative pattern of small repeating squares, most closely associated with Audemars Piguet’s Royal Oak, cut using a specialised guilloché technique. The pattern’s depth and precision, along with the difficulty of machining it consistently across a dial or case surface, are frequently cited as a mark of the model’s manufacturing complexity.

Third-party movement

A third-party movement is one designed and manufactured by an outside supplier, then purchased and cased by a watch brand rather than built entirely in-house. Many third-party movements are modified or decorated by the brand that uses them before being fitted, ranging from minor adjustments to substantial reworking of the base calibre.

Time zone

A time zone is one of the regions into which the globe is divided for the purpose of civil timekeeping, generally offset from Greenwich Mean Time in whole or half-hour increments. Watches with GMT, dual time or world time complications are built specifically to track more than one of these zones simultaneously.

Timing machine

A timing machine is a device used by watchmakers to measure a movement’s rate, amplitude and beat error by listening to and analysing the acoustic signature of the escapement. It provides the objective data a watchmaker relies on when regulating a movement to bring its rate within tolerance.

Titanium

Titanium is a lightweight metal used in watch cases and bracelets, notably lighter than stainless steel by volume while offering comparable strength and superior corrosion resistance. Its hypoallergenic properties also make it a common choice for wearers sensitive to other metals, though it is generally more difficult and costly to machine and finish than steel.

Tourbillon

A tourbillon is a complication in which the escapement and balance wheel are mounted inside a rotating cage, originally designed to counteract the effect of gravity on a pocket watch’s rate when left in a single vertical position. Its practical benefit on a wristwatch, which changes orientation constantly as it is worn, is debated among watchmakers, though it remains one of the most technically demanding and commercially prestigious complications to produce.

Trapeze cut

A trapeze cut is a gemstone cut in the shape of a trapezoid, with four straight sides and two parallel edges of differing lengths. It is used less frequently than a baguette or brilliant cut, typically appearing on bezels or lugs where its angular shape suits a specific case design.

Triplock crown

Triplock is Rolex’s proprietary name for a screw-down crown system using three sealing points rather than the two used in its Twinlock system, providing a higher water-resistance rating. It is fitted to Rolex’s professional dive models, where sealing performance under pressure is a priority.

Turning

Turning is a machining process in which a component is rotated against a cutting tool to shape cylindrical parts such as pinions, stems and certain case elements. It is one of the foundational manufacturing techniques used throughout watch production, alongside milling and CNC machining.

24-Hour Scale

A 24-hour scale is a printed or engraved marking, most often on a bezel, that allows a GMT hand to indicate a second time zone across a full day-night cycle rather than the standard 12-hour dial. It is what allows a single extra hand to distinguish between morning and evening in the second time zone being tracked.

Twinlock crown

Twinlock is Rolex’s proprietary name for a screw-down crown system using two sealing points to protect the movement from moisture and dust. It is fitted across much of Rolex’s core collection, with the higher-specification Triplock system reserved for its professional dive watches.

W

Water resistance

Water resistance is a case’s ability to withstand water pressure without allowing moisture inside, achieved through gaskets, sealed crowns and, in some designs, a monobloc construction. It is expressed as a depth rating tested under laboratory conditions, and is not equivalent to a guarantee of performance at that exact depth in real-world diving or swimming.

White gold

White gold is a gold alloy mixed with white metals such as palladium or nickel to neutralise gold’s natural yellow tone, then typically finished with a rhodium plating for extra brightness. That rhodium layer wears over time and requires periodic replating to maintain the metal’s bright white appearance.

World time

A world time complication displays the current time in multiple cities simultaneously, typically through a rotating city ring around the dial’s outer edge paired with a 24-hour display. It allows a wearer to read the time in any of the represented time zones at a glance, without needing to calculate an offset.