When a watch says “Quartz," it means that the watch is powered by a movement which regulates time through the use of a crystal made out of the mineral quartz. Quartz watches still have gears to turn the hour, minute, and second hands (unless the watch does not have hands, i.e. digital watches), as well as any other complications (explained later), but gears in a quartz watch are turned by an electric stepping motor (a motor that can move a prescribed distance each time it is engaged) that is powered by a battery.

The mineral quartz has the property of being piezoelectric. This means that when any type of mechanical stress is introduced to the material's structure, it produces an electrical impulse. The opposite is also true, meaning that the material vibrates when charged with electricity.

The basic concept behind a quartz watch movement is relatively simple. A tiny circuit and microchip use a battery to charge a tuning-fork-shaped quartz crystal, causing it to vibrate or oscillate. The microchip is calibrated to measure this vibration in order to regulate an electrical signal that pulses exactly once every second (32,768 oscillations/second!). This electrical pulse tells the stepping motor to turn the hands one second worth of motion.

Quartz is an extremely abundant mineral and the workings of a basic quartz movement are fairly easy to mass produce. Consequently, quartz watches can be produced for very low cost while maintaining a high level of accuracy. Interestingly enough, a quality quartz watch will keep time as good or better than the highest-end mechanical watches.