Updated 26th February 2025 | Words by Matt Jones @ WildBounds HQ
Case. Crystal. Lume. Bezel. When it comes to watchmaking, there seems to be a whole host of jargon referring to the various different parts of a wristwatch. Some are probably familiar, or at least easy enough to work out, but others might need a little explanation, particularly if you’re new to the world of watches. Which is why we decided to break it all down for you. To start, here's a handy illustration, based on a typical dive watch. So, if you’re interested in the (dangerously addictive) world of watches, take a look at our concise glossary of common watch terms. You’ll be more than familiar with elementary horology in no time at all.
Glossary of Common Watch Terms
Bezel The bezel is a metal ring surrounding the watch face, which helps to hold the crystal in place. On sports or tool watches, it also has additional timekeeping functionality and may rotate accordingly. There are numerous different types of bezel scales, including tachymeters, pulsometers, telemeters, decimeters, GMT bezels, compasses, count-up and countdown timers, yacht-timers and slide rules.
The most common type is a count-up bezel, used on divers’ watches for calculating elapsed time. It features a scale from 0 to 60 around the bezel, aligning with the minutes in the hour. The first 15 or 20 minutes are typically marked in one-minute increments. This is designed to ensure the diver does not run out of air during a dive. ISO 6425 is the international standard for dive watches, which dictates that a dive watch should be fitted with a unidirectional bezel that only rotates counter-clockwise. This is a safety feature, as it means that if you accidentally bump the bezel while diving, you can only have less time and more oxygen mix in your SCUBA tank. For similar reasons, the bezel on a divers’ watch is often ratcheted to help prevent it from being knocked out of its set position.
Case The case forms the main body of the watch, and houses the dial, movement and other working parts, as well as the battery in a quartz watch. More than any other aspect of a watch, it dictates a timepiece’s overall look and feel, as well as how it ‘wears’ on the wrist.
Cases come in several different shapes and styles: round, square, rectangular (often called a ‘tank’ watch), cushion, tonneau (or ‘barrel’ case) and so on. They can also be made from different materials, most commonly steel but also titanium or bronze. Similarly, they can be finished in a host of different ways: polished, brushed or bead- and sand-blasted steel, gunmetal or black, usually attained via the use of a PVD (physical vapour deposition or DLC (diamond-like coating) treatment.
The majority of watch cases are machined from 316L marine-grade stainless steel. This grade of steel has improved corrosion resistance and a low carbon content, which makes it well-suited to outdoor and marine environments.
Caseback A caseback is screwed or bolted to the rear of the watch case and gives access to the inner workings of the watch. It is usually a steel disc, frequently engraved or inscribed with decorative elements as well as details like the model of the watch, its serial number, place of manufacture and internal movement. Some watches feature transparent ‘display’ or ‘exhibition’ casebacks made of glass or sapphire crystal. These allow the wearer to inspect the workings of the watch movement.
Complications This is the term given to the additional functions of a watch: basically, anything it does beyond telling the time. There are innumerable complications, from watches that depict the phases of the moon to perpetual calendars, often shown via the use of sub-dials on the face of the watch itself.
Crown The crown is placed at the edge of the case and consists of a winder and stem. It is usually found at the 3 o’clock position, though it is sometimes placed at 4 o’clock to be less obtrusive, and occasionally at 9 o’clock on watches with a left-hand crown. It is used to set the time, and often the day/date too, by pulling it out to two or three positions and then turning it either clockwise or counter-clockwise, depending on the type of movement. On manual mechanical watches and automatic watches that can be hand-wound, it is also used to wind the mainspring of the watch. Sports watches typically have a screw-down crown, to guarantee water resistance. After adjusting the time or date, the crown needs to be screwed back into the watch case for the crown seal to become operative.
Crystal The transparent ‘glass’ of a watch is technically known as the watch crystal. They can be domed, flush, recessed or sometimes even protrude from the surface of the bezel. They are also sometimes bevelled at the edge, which helps to prevent them from chipping. Many have anti-reflective coatings to improve watch readability.
Crystals are either made from plastic/acrylic, mineral glass or sapphire. Synthetic sapphire is made by crystallizing pure aluminium oxide at very high temperatures. It forms one of the hardest substances on earth, so is highly scratch resistant.
Date window Sometimes called a date aperture, this is a small window in the dial of the watch that shows the numeric date. Some watches have no date window at all, some have only a date aperture, others have a day-date aperture that also indicates what day of the week it is. Date windows are usually – but not always – placed between 3 and 6 o’clock on the dial for the sake of legibility and design harmony.
Dial Also known as the face, the dial is the part of the watch that displays the time, via printed numbers (indices) and/or hour and minute markers. It sits beneath the hands and may incorporate raised hour batons and sub-dials. The dial usually also features the brand name and logo, as well as other details like the movement type (automatic or quartz), place of manufacture – particularly if Swiss or Japanese – and degree of water-resistance (in metres, atmospheres or bars). The dial is surrounded by a chapter ring and protected by the crystal and bezel.
Hands Most watches have a shorter hour hand, a longer minute hand and a thinner seconds hand, which work together with the dial to display the time. GMT watches also have a fourth hand, which indicates the time in an additional time zone.
Indices The indices are the numbers of a watch as printed on the dial. Classic indices use Arabic numerals from 1-12, or roman numerals from I-XII. Some watches show a mix of Arabic and roman numerals, which is known as a ‘California’ or ‘Cali’ dial. In addition, many specialist watches display 24-hr markings, while some – particularly pilot or aviator watches – tend to show the minutes more prominently than hours. Other watches omit indices altogether, instead displaying the hours via markers or batons.
Lugs These are the shoulders protruding from the top and bottom of the case, which enable the watch to be attached to a strap, band or bracelet via strap bars.
Lume Short for luminescence, ‘lume’ is the term that refers to any part of the watch that glows in the dark, enabling the time to be read at night or in low-light conditions. Provided the watch has had a good ‘charge’ for a few hours in daylight, good quality lume (such as SuperLuminova) should last for up to 8 hours.
Movement A movement or calibre is the internal mechanism that operates the watch. Movements can be either quartz or mechanical. Quartz movements are very accurate and powered by a cell, button or coin battery, with few moving parts. The battery sends an electrical current through a small quartz crystal, electrifying the crystal to create vibrations. These vibrations keep the movement oscillating and drive the motor to move the watch hands.
A mechanical movement uses energy from a mainspring to power the watch. This spring stores energy and transfers it through a series of gears and smaller springs. Mechanical movements can be manual (hand-wound) or automatic (self-winding). The former require regular winding via the crown, while the latter harness energy through a rotor, which is activated via the natural motion of the wearer’s wrist. As long as the watch is worn regularly, it will maintain power without requiring winding, though many modern automatic watches can also be wound by hand. In addition, many have a ‘hacking’ function, which is the ability to stop the movement at will by pulling out the crown. It is useful for synchronizing a watch with another, or with an atomic/radio-controlled clock.
An easy way to tell a quartz from a mechanical movement is by looking at the seconds hand. Quartz watches have a regular ‘ticking’ seconds hand, while mechanical watches have a smooth, sweeping seconds hand.
Pusher This is the secondary button on the side of a watch, in addition to the crown, that operates other functions such as the chronograph.
Strap Bars These metal bars are usually hidden from view. They are usually sprung, and sit between the lugs of the watch. To attach a watch to a strap, the bars are threaded through holes in the ends of the watch strap (or the end links of a metal watch bracelet). With a NATO strap, the strap is threaded over the bars and underneath the caseback of the watch itself.
Strap Usually referred to as a ‘watch band’ in the US, this is how a watch is attached to your wrist. It usually incorporates a buckle and at least one keeper or loop. Straps are traditionally made of leather or metal (in which case it is usually referred to as a bracelet), but can also be made of canvas, rubber or synthetic fabrics such as nylon webbing.
