The Bench · N° 01

What the jewels in a watch movement actually do

Synthetic ruby bearings reduce friction and wear at small, heavily loaded contact points. The jewel count tells you how many are used, not how well the movement is made.

Hen & Mills Editorial · 4 min read · 9 August 2026

The jewels in a watch movement are functional bearings, not hidden decoration. Most are synthetic ruby, chosen because it is hard, smooth, stable and can be manufactured to precise dimensions.

They support rotating pivots, control sliding contact in the escapement and reduce wear where very small surfaces carry repeated loads.

A movement needs the right jewels in the right places. A larger count is not automatically better.

Why metal against metal is a problem

A wheel pivot may rotate millions of times while resting in a tiny bearing hole. If both surfaces are metal, friction and wear can change the fit and consume energy.

A hard polished jewel provides a durable contact surface. Its low wear helps the pivot remain correctly positioned over long service intervals.

Lubrication is still normally required. The jewel improves the bearing; it does not remove every source of friction.

Synthetic ruby

Watch jewels are generally laboratory-made corundum coloured red with chromium. Chemically and physically, the material is closely related to natural ruby.

Synthetic production avoids the flaws, inconsistent sizes and cost of cutting suitable bearings from natural stones. It also allows industrial quantities of standardised parts.

Their value is technical. A pile of watch jewels has little relationship to the retail value of gem-quality natural rubies.

Hole jewels

A hole jewel is a small disc with a precisely formed opening. A wheel pivot runs in that opening.

The hole controls the pivot's lateral position while allowing it to turn. Its shape, polish and fit influence friction and the stability of the gear train.

Oil is placed in a controlled amount at the contact. Too much, too little or contaminated lubricant can undermine the benefit of the bearing.

Cap jewels

A cap jewel sits against the end of a pivot and controls movement along the pivot's axis. Paired with a hole jewel, it forms a compact bearing system.

The cap also helps hold lubricant around the contact area through surface tension.

Balance pivots commonly use jewelled settings with shock protection because they are fine and vulnerable to impact.

The escapement jewels

The pallet fork normally carries two pallet stones that lock and release the escape wheel. A roller jewel on the balance interacts with the fork to transfer impulse and release the escapement.

These are not simple round bearings. Their shapes and positions are part of the escapement geometry.

Adjustment affects locking, draw, impulse and energy loss. Counting the stones does not show whether that adjustment was done well.

A familiar 17-jewel layout

A basic hand-wound movement with 17 jewels can place bearings at the balance, pallet fork and principal train wheels, plus jewels in the escapement.

That count became associated with a fully jewelled conventional movement because it covers the important high-speed and high-load points in a simple layout.

It is not a universal ideal. Different architectures need different numbers.

Why automatic watches use more

An automatic winding system adds a rotor, reversing wheels and other moving parts. Some of those contacts benefit from jewelled bearings.

A date mechanism, chronograph or extra barrel can also add legitimate jewel locations.

The count should rise when the mechanism creates useful bearing points, not merely because a larger number looks impressive on the rotor.

When extra jewels do little

Jewels can be placed where loads and movement are too small to justify them, or even attached without a genuine bearing function. Historically, inflated jewel counts were used as a sales tactic.

Modern buyers should remain cautious about judging movements from the number alone.

A 21-jewel movement is not automatically superior to a 17-jewel one, and a 50-jewel complication may simply require more bearings.

Jewels can still wear or break

Synthetic ruby is hard but brittle. A strong impact can chip a jewel, and a damaged pivot can score or enlarge its hole over time.

Dried or contaminated oil can create abrasive wear. A loose setting can let the jewel move.

During service, the watchmaker inspects the jewel, pivot and oil sink rather than assuming the red part must be fine.

Pressed and set jewels

Many modern movement jewels are friction fitted directly into plates and bridges. Their depth can control endshake, so installation is a precision operation.

Traditional chatons hold a jewel in a separate metal setting, sometimes secured with screws. They can be visually attractive and historically important.

A chaton is not required for the jewel to work well. It is a different construction and finishing choice.

Do quartz watches use jewels?

Some analogue quartz movements use jewels at motor and gear-train bearings. Others use different low-friction materials or reduce the count because their load and motion differ from a mechanical calibre.

A low jewel count in quartz is not evidence of a fake or disposable movement. The design determines where hard bearings are useful.

Digital watches can have no moving display train at all.

What the count can tell you

Jewel count may help identify a movement variant or suggest the presence of automatic winding and complications. It can also confirm that major pivots are jewelled in a traditional design.

It cannot tell you the quality of the gear teeth, finish, lubrication, regulation or service history.

For those questions, movement documentation, inspection and measured performance are better evidence.

Small bearings, not a score

Watch jewels solve a practical tribology problem in very little space. They provide hard, smooth surfaces where metal pivots and escapement parts would otherwise wear quickly.

Their success is one reason they are easy to overlook: a correctly fitted jewel spends its life quietly supporting another component.

Count them if the architecture interests you. Judge the movement by whether each bearing is necessary, correctly made and properly serviced.