Movements: The Inside Story

As we’ve seen, there are two categories of watch movements, quartz and mechanical. The main parts of an analog quartz watch movement are the battery; the oscillator, a piece of quartz that vibrates in response to electric current; the integrated circuit, which divides the oscillations into seconds; the stepping motor, which drives the gear train; and the gear train itself, which makes the watch’s hands move. A digital watch movement has the same timing components as an analog quartz movement but has no stepping motor or gear train. In fact, it has no moving parts at all, which is why it is usually called a module rather than a movement.

The main parts of a mechanical watch movement are the winding mechanism; the mainspring, which is the source of the watch’s power; the gear train, which transmits power from the mainspring to the escapement and drives the watch’s minutes and seconds hands; the escapement, which distributes power to the oscillator (i.e., the balance) and controls how fast the mainspring unwinds; the balance itself, which measures out time by vibrating at a steady rate; and the motion works, which moves the watch’s hour hand.

Most mechanical and quartz analog watch movements are made by one of three companies: Citizen, Seiko, (both are Japanese firms) or Switzerland’s ETA (pronounced EE-tuh), which is owned by the huge Swatch Group watch conglomerate. There are several smaller watch movement companies: Ronda, ISA (pronounced EYE-suh), and others. Modules for digital watches are made by various companies, most of them in China.

Most watch companies buy the movements, case them and sell them under their own brand names.

Some watch companies buy movements and modify them for use in their watches. They can add certain functions-chronographs and calendars, for example. In most instances they purchase these add-on functions, often called modules, from movement makers. Companies can also engrave or finish the movements they buy. Some brands, for instance, finish their movements with a pattern called cotes de Geneve, pronounced “cote de Gen-EV,” which translates as “Geneva stripes”

A few watch brands make their mechanical movements from scratch. If a watch company itself makes at least one of the various movements that it incorporates in its watches, it’s entifled to call itself a manufacture, pronounced “man-u-facTUHR”-French for “manufacturer:’ We say “entitled” because a company’s ability to produce its own mechanical movements enhances its prestige-in some people’s eyes, at least.

The word caliber (or calibre) is used to specify a certain type and size of movement. It’s used for both mechanical and quartz analog movements. Movement makers like ETA and watch companies that make their own movements or modify ones they purchase number their calibers for easy reference.

Most often the number is preceded by a name or initials indicating the watch brand, movement name or movement company. For example, one well-known caliber is the Valjoux (pronounced “val-JOO”) 7750, an automatic chronograph movement made by ETA.

Both mechanical and quartz analog movements often incorporate jewels, round bearings used to decrease friction between moving parts. They’re made of synthetic ruby, or, less often, synthetic sapphire. (Ruby and sapphire are both forms of corundum, a very durable mineral, which is also used to make scratch-resistant watch crystals. Even though they’re made of sapphire, watch jewels have almost no intrinsic value.

Some watch movements have undergone testing at an independent testing bureau in Switzerland to measure their accuracy. If they pass the bureau’s strict standards, the movements are certified as chronometers. They are not to be confused with chronographs The testing agency is the Controle Officiel Suisse des Chronometres, abbreviated “COSC.” It has testing facilities in three Swiss cities and each year issues about 1 million certificates.

Chronometers can be mechanical or quartz. The standards for quartz are higher because of quartz’s greater inherent accuracy. The vast majority of COSC-certified movements, though, are mechanical ones. Chronometers are usually, but not always, labeled as such on the dial.

A chronometer is not necessarily more accurate than a non-chronometer. Many high-quality movements aren’t submitted to COSC and therefore aren’t eligible to become chronometers. COSC certification does nonetheless guarantee a high level of accuracy, and some consumers think the premium they pay for that guarantee is well worth the money.

There’s another honor bestowed on some watches, albeit fewer than 50,000 of them a year. It’s called the Geneva Seal, or, in French, the Poincon de Geneve (pronounced PWANSOHN de gen-EV). A bureau in the Swiss city of Geneva issues the seal to watch movements on the basis of the quality of their workmanship. Only mechanical movements made by Geneva companies are eligible for the seal. Those that pass muster receive a special hallmark on the movement plate.