Watch Glossary of Terms

Amplitude

Sometimes used to describe the frequency of a mechanical movement, however seems more often used to describe the angle of oscillation of the balance wheel either side of its neutral position. This would therefore be measured in degrees, for example 'an amplitude of 270 degrees'.

Analogue

Analogue simply refers to the means of showing the time on a watch dial by means of hands which point to the hours, minutes and usually seconds.

Anchor

The anchor, sometimes referred to as Swiss anchor helps perform the final part of the mechanical process in a mechanical watch in order to divide the seconds and provide accurate timekeeping. Moving side to side, the anchor allows the final wheel (escape wheel) to rotate one cog at a time. This process produces the ticking sound of a mechanical watch.

Blued Screws

Traditionally, high quality movements were fitted with screws which were artificially blued, more for decoration than function.

Breguet Hands

A style of watch hands designed by Abraham Louis Breguet (1747-1823), one of the most famous watchmakers of all time.

Chronometer

Technically means an instrument which measures time (a watch). Swiss watches described using this term usually mean the watch is COSC tested and approved for accuracy by the government approved, Controle Officiel Suisse de Chronometrage.

Crown

The crown, often referred to as the winding crown or winder is used for winding the watch in the case of a non-automatic, for setting the hands to the correct time and often for setting the date in the case of calendar equipped watches.

Screw Crown

On diving/sports models, the crown may be screw down tightly, whereby it screws onto a threaded tube which protrudes from the case of the watch. This often ensures superior water resistance.

Crystal

The crystal is the clear cover over the dial.

Acrylic Crystal

Sometimes referred to as Hesolite or Hesalite, an acrylic crystal is basically plastic. Benefits of an acrylic crystal are that is flexes rather than shatters on impact, it doesn't produce too much glare under bright light and it can be polished easily.

Mineral Crystal

Basically fancy name for hardened glass used to make scratch resistant watch crystals. More scratch resistant than acrylic, a mineral crystal will however scratch and is extremely difficult, if not impossible to polish.

Sapphire Crystal

Synthetic Sapphire is used to make a totally scratch proof watch crystal. Only a diamond is able to scratch sapphire. Extremely scratch resistant (9 on the Moh scale), a sapphire crystal is the material of choice for many watch collectors. The downsides are that sapphire can chip at the edges if they protrude and can shatter.

Dial

The dial, often referred to as the face is usually marked with numbers or batons to which the hands point in order for the wearer to tell the correct time. Dials themselves can be very simple, sometimes with no markers at all or extremely complex as in the case of pilots' chronographs. Dials can be decorated with patterns or in some cases with precious stones.

Display

The way the time is shown on the watch.

Analogue

Traditionally, watches have displayed the time in analogue form, with a numbered dial upon which are mounted at least a rotating hour hand and a longer, rotating minute hand. Many watches also incorporate a third hand that shows the current second of the current minute

Digital

A digital display simply shows the time as a number, e.g., 12:08 instead of a short hand pointing towards the number 12 and a long hand 8/60 of the way round the dial.

LCD

Or Liquid Crystal Display; used for the display on most modern digital watches. The LCD was preferred as it used vastly less power than the LED thus the time could be shown constantly as opposed to having to press a button for time display.

Ebauche

An industry term for a base mechanical watch movement before any modification

EOL

Battery End Of Life indicator. This function forewarns of impending battery failure in a quartz watch by means of the second hand jumping in two or sometimes four second intervals approximately two weeks before battery failure.

Frequency

Amplitude, in the case of mechanical watches refers to how many times an hour the watch goes tick for a given time period! It is often referred to as half-swings per hour or beats per hour (BPH). Thus a watch beating at an amplitude of 28,800 per hour ticks 8 times per second.

Gear Train

The gears used in a mechanical watch which run from the mainspring which powers the watch through to the escapement which translates that power into timekeeping.

Geneva Stripes

A form of decoration in higher grade watch movements which look like stripes on the movement plates. These used to be applied by hand; in many cases in modern times, they are very simply applied by machine.

Guilloche

Refers to the special texturing or machining of a surface on a watch dial, generally a detail found on finer timepieces.

Hack/Hacking

Describes the feature of a movement whereby the seconds hand can be stopped for exact setting of the time. Originally a military term for this feature.

Index/Indices

Usually refers to the markings on the dial of a watch showing hours and minutes. Can however refer to the markings on the regulator of a watch movement to aid precision adjustment for accurate timekeeping.

Jewels

In all watches, the power must be transmitted from the main energy source all the way to the hands. This power transmission takes place through many rotating parts. Whenever there is a rotating component, there is friction which reduces the watches accuracy and takes away valuable energy the watch needs to keep running.

To minimize friction, watches are fitted with synthetic rubies on most gear pivots. The ruby is lab created, is generally round, and has a small hole in it for one end of the gear to fit in. The gears itself rotates in these rubies. The rubies contain a small drop of lubrication to further minimize friction.

To simply transfer energy from the mainspring to the hands, about 17 jewels are needed. There is a common misconception that more jewels is better; this is not true. More jewels only means there are more rotating parts and the movement is more complex. For instance, a chronograph complication adds more rotating parts and requires 23 jewels; the same movement with a moon phase indicator is 25 jewels.

Lugs

Protrusions on the case of a watch to which the bracelet or strap is fitted. Various types of lugs can be found such as rounded lugs, teardrop lugs and hidden lugs.

Luminescent Hands/Dials

Hands and indices on a watch that glow in the dark after being "charged" by a light source (usually a strong light for 30 seconds or so).

Movement

Simply used to describe the workings or engine(!) of a watch, be it mechanical or quartz. Often referred to as a calibre by manufacturers.

Mechanical Movement

Used to described a watch movement that doesn't require a battery. There are two types of mechanical movements – hand wound and automatics.

Manual

Simply a watch who's main spring must be wound manually by turning or rotating the crown.

Automatic

A style of watch that has a main spring that is wound by the movement of the wearer's wrist. This is accomplished by means of a rotor inside the watch that swings freely on its arbor to wind the main spring.

Quartz Movement

A battery operated movement which uses the vibration frequency of quartz crystal to regulate the operation of the watch.

ETA Movement

ETA is a Swiss producer of mechanical and quartz watch movements and also manufactures clock movements, as well. It is a wholly owned subsidiary of the Swatch Group.

Valjoux Movement

Valjoux (for Vallée de Joux, "Joux Valley") is a Swiss manufacturer of mechanical watch movements that specializes primarily in chronograph production.

O-Ring

O rings are used to seal the backs of watches which feature either a press-in back or a screw on back. They ensure water resistance. Usually also used on the winding stems of watches and in the winding crowns to protect against the ingestion of water and dust. Normally made from a rubber/plastic compound.

Register

Another name for a sub-dial; this is usually a dial within the main dial of a watch. The best example is possibly a chronograph where there may be registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.

Rotor

The oscillating mass which winds an automatic movement. A rotor most commonly is free to rotate in a full 360 degrees and may wind the watch when it is rotating in one direction only or indeed may wind in both directions through the use of reverser wheels and gears. 

Shock-Resist

Describes a watch that has certain components of the movement protected by shock absorbing devices. Most often the escapement of the movement is protected by such, more specifically the balance staff.

Sub-Dial

See Register above; a dial within or on the main dial of a watch.

Tritium

An isotope of hydrogen used in the luminous compounds which give watch dials and hands their glow in the dark capabilities. Many watch dials will show a small T at the bottom, indicating the use of tritium. The half life of tritium is 12.5 years thus it will lose its ability to provide illumination as time passes. Now largely superceded by non-radioactive organic compounds such as the trade name Luminova.

Water Resist

Watches have varying degrees of water resistance, ranging from WR30 Meters to some specialist watches having a capability of withstanding water to 10000 Meters. The usual for a diver's watch is 200m whilst 100m would be suitable for everyday swimming.