The short answer
An automatic movement is mechanical: it winds itself from the motion of your wrist, its seconds hand sweeps, and it needs no battery, but it gains or loses a few seconds a day and wants servicing every few years. A quartz movement runs on a battery, keeps time to within seconds a month, and asks for little more than a new battery. Choose automatic for the craft, quartz for the convenience.
Beneath every gem-set watch is one or the other, and each listing names which. Here is how they differ, and how to choose.
How an automatic works
An automatic is a mechanical watch that winds itself. A weighted rotor turns with every movement of your wrist and winds the mainspring, which stores the energy. The escapement releases that energy in measured beats to the balance wheel, whose steady oscillation keeps time. No battery is involved at any point.
Two figures describe an automatic. The beat rate is how many times the balance vibrates each hour; a widely used Japanese calibre such as the Miyota 8215 beats at 21,600 vibrations per hour, which gives its seconds hand the characteristic sweep. The power reserve is how long it runs once taken off; for the Miyota 8215 the maker specifies more than 40 hours. Wear it daily, and it never stops.
How quartz works
A quartz movement is electronic. A battery sends current through a tiny quartz crystal, which vibrates at exactly 32,768 times a second. A circuit counts those vibrations and, once a second, drives a small motor that advances the seconds hand — the familiar step.
The crystal’s stability is what makes quartz so accurate, and the simplicity of the movement is what makes it slim, light and durable.
Accuracy
Quartz wins. A typical quartz watch keeps time to within about 15 seconds a month. A mechanical automatic is measured in seconds a day: the Miyota 8215’s maker specifies between 20 seconds slow and 40 seconds fast per day. In practice, an automatic worn daily is set a few times a month; a quartz watch is set when the clocks change.
For many owners that difference is the point rather than the problem. An automatic is a small machine you can feel working; its variances are the character of a mechanism, not a flaw.
Care, winding and servicing
- Automatic. Wear it, and it winds itself. If it stops, give the crown a few turns — most calibres, including the Miyota 8215, can be wound by hand — then set the time. A watch winder keeps it running between wearings. Keep it away from strong magnets, and have it serviced every three to five years.
- Quartz. Replace the battery when the seconds hand begins to jump in several-second steps, which is the usual signal that it is low; batteries typically last 18 to 24 months. Replace a dead battery promptly, because an exhausted cell can leak. Beyond that, quartz asks for very little.
Other movements you may meet
- Hand-wound mechanical: an automatic without the rotor. You wind it by the crown, usually each morning — a small daily ritual some owners prize.
- Solar quartz: a quartz movement whose cell is recharged by light through the dial. Rare on gem-set watches, since a set dial admits little light.
- Meca-quartz: a quartz movement with a mechanical chronograph module, giving the snap-back feel of a mechanical stopwatch with quartz accuracy.
Reading a movement on a listing
A good listing names the calibre, not just the type. “Japanese automatic” tells you the category; “Miyota 8215” tells you the exact movement, its beat rate, power reserve and accuracy, all published by its maker. Other terms you may see: jewels, synthetic rubies used as low-friction bearings (21 is typical for a basic automatic); hacking, a seconds hand that stops when the crown is pulled, for precise setting; and hand-winding, the ability to wind an automatic by the crown.
Seeing the movement
Some automatics carry an exhibition case back — a sapphire or mineral window in the back of the case — so you can watch the rotor turn and the balance beat. On a gem-set watch it is a quiet pleasure: the stones face the world, and the mechanism is yours alone. A quartz movement is rarely shown, since there is little to see, which is one reason quartz case backs are usually solid steel.
Which suits a gem-set watch
Consider how often you will wear it. A statement watch kept for evenings and occasions is often better as quartz: it is set and ready whenever you reach for it. A watch worn every day rewards an automatic, which stays wound and gives you the sweep of a mechanical seconds hand beneath the stones.
Consider thickness, too. Automatic movements are taller, so an automatic case sits a little higher on the wrist; if the watch must slip beneath a shirt cuff, a quartz dress watch is the slimmer choice. Our case size guide covers thickness in detail.
Neither is the lesser watch. Browse men’s analog watches or women’s analog watches — every listing names the movement inside.