A complicated watch which automatically makes allowance for the length of the month i.e. 30 or 31 days.

Used in mechanical watch movements.

To bevel or “chamfer” involves removing sharp edges carefully using a lathe or file.

To ensure improved corrosion resistance, hands are heated to a high temperature (approximately 300° C) to make them turn blue.

A term often used to describe a metal link watch band fitted with a clasp.

A metal plate fastened to the base plate of the movement at two or more points to allow moving components to move beneath.

This is a term often used to describe the movement within a watch.

A Chronograph not only shows the time of day but also includes a stop-watch facility for measuring a time interval and displaying it with a dedicated seconds hand, together with elapsed minutes and hours often shown on sub dials.

This term is used to describe a mechanical watch with a high level of accuracy.

The cock (or bar) is a metal plate which is attached to the base plate at one point, allowing room for a balance wheel to be located underneath.

The crown is used to wind the mainspring as well as adjust the time displayed on the watch.

This is a term given to a clasp on a watch strap which provides a more complex and expensive alternative to the pin-buckle.

A glass-like substance that is used in the form of coloured enamel powders which are mixed with special oils and applied like paint.

The art of engraving is employed in haute horology to adorn the case and the movement using burins (a special chisel type tool).

The Escape Wheel, Pallet Fork, Balance Spring and Balance wheel form the Escapement which controls the energy from the Spring Barrel and converts it into accurate, portions of energy to ensure that the gear train runs smoothly and accurately.

Finissage or “Finishing” is the term given to time-consuming bevelling, guilloché, engraving, anglage, perlage, and polishing associated with fine watchmaking.

The Gear Train transfers power from the Mainspring to the balance wheel.

Geneva Stripes sometimes called “Côtes de Genève”.

A variation of “Geneva Stripes” found on movements from Glashütte watchmakers.

GMT is a term used to describe a watch which carries an additional hour hand that can be adjusted by the wearer to indicate the hours in another time zone.

Originally a plate would have been drilled to accommodate rubies to reduce friction.

Pushing a ruby into the drilled hole would be simple but may have resulted in the jewel becoming damaged.

Guilloché is a traditional surface decoration applied to the dial or rotor (on automatic movements), created using a grooving tool with a sharp tip to create an even pattern on the surface.

When diving at great depths, divers will acclimatise within a diving bell to increase their tolerance to the pressures at the working depth.

The steel spring on the movement shown is pressed against the tip of a small screw. By turning this screw in or out, the rate of the movement can be adjusted.

The friction of the rotating gear wheels within a traditional pocket watch movement was often reduced by using rubies lubricated with a very thin layer of special oil.

A complication using hammers and gongs to deliver chimes to signify hours, quarter hours and minutes.

Surface decoration featuring overlapping circles created with a rapidly rotating wooden peg.

A Perpetual Calendar typically displays date, month, year and sometimes moon phase too.

The pin buckle sometimes called a tang buckle is fitted to a strap and provides a cheaper alternative to a deployant.

The indicator shows the amount of power held within the mainspring expressed in terms of days.

A French word used to describe a split seconds chronograph.

Unlike a standard chronograph, the split seconds chronograph has two hands that start simultaneously.

The rotor is an eccentric weight found in automatic watches, often semi-circular in appearance which turns on a pivot and winds the mainspring when the wearer’s wrist moves.

Panerai offer some models featuring a sandwich dial which involves a dial consisting of numbers and indices cut out to reveal a second luminous dial beneath.

Synthetic sapphire crystal is made from Aluminium Oxide into a clear colourless, fully transparent material.

A screwed balance contains small weighted screws which can be adjusted to achieve the desired inertia.

The spring barrel contains the mainspring which stores the energy to drive the gear train.

Typical of A. Lange & Söhne, an untreated silver plate is drilled and simultaneously positioned onto several arbors.

Tourbillon means “whirlwind” and is regarded as the ultimate watch complication.

The balance wheel oscillates anti-clock wise and clock-wise through a range of two extreme positions (typically about 300 degrees apart).