In our wristwatch glossary, you’ll find explanations of the most important terms related to watches.

Automatic Movement:
The motion of the wrist keeps a rotor—also known as a winding mass—spinning. This rotor winds the mainspring, which powers the movement.

Blued Hands, Blued Screws:
Metal parts that are heated to 290°C to relieve stress, causing them to turn blue.

Domed Crystal:
A curved glass covering the dial or case back.

Cabochon:
A decorative or precious stone that is not faceted but smoothly polished and rounded. Often used in watch crowns as ornamentation.

Chronograph:
From Greek “time writer.” A watch that includes a stopwatch function which operates independently from the main movement, recording time intervals down to the second—often up to minutes or hours.

Perpetual Calendar:
A watch with a highly complex mechanism that automatically accounts for all month lengths and leap years in the Gregorian calendar for almost 100 years without manual correction—along with displaying the date, day of the week, month, and moon phase.

Power Reserve:
The amount of time a fully wound mainspring can keep the watch running.

Geneva Seal:
A quality certification (displaying the Geneva coat of arms) stamped into the watch movement. It certifies that the mechanical watch is of high quality and assembled and regulated exclusively in the Canton of Geneva.

Geneva Stripes:
Decorative stripes applied to movement components—especially plates and bridges. These only make sense in watches where the movement is visible through a dial window or transparent case back.

Guilloché:
Intricate, fine, interwoven patterns engraved on the dial or case.

GMT:
Greenwich Mean Time – the standard reference for world time zones.

Manual Winding:
The first historical method for winding a watch’s mainspring—initially done with a key, nowadays by turning the crown. Despite the invention of automatic and electronic systems, manual winding watches remain very popular today.

Helium Valve:
Important in professional dive watches. In deep-sea diving chambers and stations, the air is enriched with helium to aid breathing. Helium seeps into watches and causes overpressure. A helium valve ("gas overpressure valve") releases the excess pressure.

Annual Calendar:
A movement that automatically adjusts the date display according to the length of the month.

Caliber:
A designation for a movement, consisting of letters and numbers that indicate the maker, series, size, and other specs. Crucial for sourcing replacement parts.

Moon Phase (Lunation):
The moon’s cycle from new moon to first quarter, half moon, last quarter, full moon, and back to new moon – approximately 29.5 days.

Quartz Movement:
An electronic movement where a vibrating quartz crystal regulates the timekeeping. Usually powered by a tiny battery or, more recently, by solar cells that convert light into electricity. Modern quartz watches are accurate to about one minute per year.

Rhodium Plating:
Galvanic refinement of metal surfaces to make them harder and more lustrous.

Sapphire Crystal:
The hardest type of crystal, made from synthetic sapphire, extremely scratch-resistant. Due to its hardness, it can only be worked with diamonds or diamond powder.

Hacking Seconds:
A mechanism that stops the second hand while the movement continues running, allowing for precise time setting.

Jewels:
Used as almost wear-free bearings for the axles of important moving parts. Originally real gemstones were used; today, synthetic rubies or sapphires are standard.

Shock Protection:
A flexible mounting of the balance wheel in the plate and balance cock to protect it from impacts, especially when the wrist is bumped or jolted.

Tourbillon:
A very complex mechanism that compensates for the effects of gravity on the balance wheel. It’s both a mechanical and visual highlight and is often displayed through a window in the dial.

Balance Wheel:
A round metal ring that oscillates back and forth, regulating the watch’s timekeeping by releasing the energy from the mainspring in precisely measured beats to the movement.