Quartz movement: how the complication works

A quartz movement replaces the mainspring, balance and escapement of a mechanical watch with electronics. A battery drives a sliver of quartz to vibrate at exactly 32,768 hertz, an integrated circuit counts those vibrations and issues one pulse a second, and a stepper motor advances the hands.

The result is a watch that is cheaper to make, far more accurate, and needs only a battery change every few years. Because a quartz caliber is dimensioned quite differently from a mechanical one, and needs a battery and a stepper in place of a rotor and barrel, swapping a quartz movement into a mechanical case, or the reverse, is a case-and-dial project rather than a drop-in.