Jewels in Watch Movements: What They Do and Why They Matter

Tufina Theorema Venezia GM-118-3 Gold - Mechanical Watch with 17 rubies.

Why Mechanical Watches Need Jewel Bearings in the First Place

Here's the fundamental challenge watchmakers have dealt with for centuries: a mechanical movement contains dozens of components spinning continuously while the watch runs. Every rotating wheel, pinion, and lever needs a bearing surface where its pivot (essentially a microscopic axle) makes contact with the movement plate or bridge holding it in position.

Think about the forces at play here. Take the balance wheel, often referred to as the beating heart of any mechanical watch. In most automatic movements, it oscillates 28,800 times per hour. 

Break that down: eight oscillations every single second, 480 per minute, 691,200 each day. The pivots supporting this relentless motion face extraordinary stress despite contact areas measured in fractions of a millimeter. When metal rubs against metal at these contact points, two problems immediately emerge. 

First, friction drains energy from the mainspring, cutting into your power reserve and reducing the balance wheel's amplitude (how far it swings with each oscillation). Second, this constant wear gradually enlarges the pivot holes, introducing play that throws off accuracy over time.

Early watchmakers used plain brass or steel plates with drilled holes for pivots. These metal bearings wore out quickly. The holes would become oval-shaped, causing the watch to run differently depending on its position. Owners needed frequent servicing just to keep their timepieces running reasonably well.

The hunt for harder, smoother bearing materials drove innovation for generations. Watchmakers experimented with various alloys and treatments, but nothing truly solved the problem until they turned to gemstones.

From Expensive Curiosities To An Engineering Standard

In the 1800s, watchmakers working on high-end pocket watches and marine chronometers discovered that natural rubies made extraordinary bearings. Ruby's crystalline structure ranks 9 on the Mohs hardness scale. Only diamond beats it at 10.

A skilled watchmaker would carefully drill a hole through a small piece of ruby, then painstakingly polish the inside of that hole until it was mirror-smooth. The resulting bearing would outlast metal alternatives by orders of magnitude while significantly reducing friction.

The catch? Natural rubies were phenomenally expensive. They also contained internal flaws that affected consistency. Natural stones varied in size and quality, making standardization nearly impossible. And obviously, there weren't enough high-quality natural rubies available to put jeweled bearings in more than a handful of luxury timepieces.

Everything changed in 1902 when French chemist Auguste Verneuil perfected his flame-fusion process for creating synthetic rubies. His technique produces pure corundum crystals without the inclusions that plague natural stones. The resulting synthetic rubies match—or even exceed—natural stones for watchmaking purposes, but at a fraction of the cost.

Modern synthetic rubies used in watch movements achieve remarkable purity. Manufacturers can specify exact dimensions, hardness characteristics, and optical properties with precision that would have seemed like magic to early watchmakers. That red color comes from trace amounts of chromium, chemically identical to what colors natural rubies.

The availability of affordable synthetic jewels completely transformed watchmaking. Jeweled movements went from being exclusive luxuries to standard practice. Today, even entry-level mechanical watches incorporate jewel bearings at critical friction points. 

This democratization of quality is something we take seriously at Tufina. We believe precision engineering shouldn't be reserved only for collectors spending five figures. Quality watches should be accessible to everyone at different price points.

How Jewels Actually Protect Your Movement

Jewel bearings serve three distinct functions within a mechanical movement. Understanding these roles explains why jewel count alone doesn’t tell you enough about quality. Placement and implementation matter just as much.

Hole jewels are the most common type. These donut-shaped jewels fit into movement plates and bridges, providing bearing surfaces for wheel and pinion pivots passing through them. The pivot rotates within the jewel's polished center hole. 

Getting this right requires precise tolerances: the hole diameter needs to be tight enough to prevent lateral play (unwanted side-to-side movement) but loose enough to avoid binding and excessive friction.

Cap jewels cover hole jewels at high-wear locations, creating complete bearing surfaces both above and below pivots. The balance wheel staff particularly benefits from this treatment. Since the balance oscillates constantly at high speed, cap jewels distribute wear across larger surface areas while creating a small cavity that traps lubricant between the hole and cap jewel. This lubrication retention significantly extends the time between service appointments.

Pallet jewels appear in the escapement mechanism. These jewels endure extreme forces during each tick as they interact with the escape wheel. Their hardness prevents wear that would quickly affect timing accuracy. The impulse jewel on the balance staff similarly benefits from ruby's durability during its repeated contact with the escapement.

Installing these bearings is precision work. Jewels must sit perfectly perpendicular to the pivots, with holes precisely concentric to their mounting locations. Even slight misalignment creates uneven wear patterns that affect long-term accuracy.

The entire bearing system works optimally only when properly lubricated. Watchmakers apply microscopic quantities of specialized oil to jewel bearings during assembly. The jewel's smooth surface helps retain this lubrication while minimizing oil migration to where it doesn't belong. 

However, lubricants gradually break down over time, which is why periodic servicing remains necessary even with jewel bearings protecting your movement.

Quality jewel implementation shows in detail invisible without magnification. The jewel holes should exhibit mirror-polish interiors. Jewel settings should seat firmly without gaps. Pivots should appear centered within jewel holes across all positions. These execution details separate excellent movements from merely adequate ones.

Decoding Jewel Count Numbers

Walk into any watch shop and you'll see jewel counts proudly displayed in specifications: 17 jewels, 25 jewels, 31 jewels. But what do these numbers actually mean?

A basic manual-wind movement requires seventeen jewels for complete jeweling of essential components. This standard configuration includes hole jewels for the fourth wheel (which drives the seconds hand), third wheel, center wheel (which drives the minute hand), and seconds wheel. 

The escape wheel gets both the hole and the cap jewels, given its critical role in the escapement. The pallet fork receives jeweled pivots. The balance staff gets the full treatment: whole jewels, cap jewels, and the impulse jewel.

Automatic movements add jewels for the rotor system that winds the watch as you move your wrist. A quality automatic watch  typically features 25-27 jewels. Those additional jewels support the rotor's bearing, the reversing wheels that transfer rotor motion to the mainspring, and the automatic train wheels. 

These aren't just marketing fluff. Automatic winding mechanisms experience constant motion whenever you're wearing the watch, absolutely justifying jeweled bearings at these friction points.

Higher jewel counts many times indicate legitimate quality improvements. Premium movements might include additional wheels in extended power reserve systems or complex calendar mechanisms. Chronograph complications require jewels for the additional wheel trains. 

However—and this is important—jewel count inflation has occurred historically when manufacturers added functionally unnecessary jewels purely for marketing differentiation. Some vintage movements featured jewels in locations experiencing minimal wear or rotation. The jewels technically existed, but they weren't actually doing anything useful.

How do you evaluate jewel count properly? Consider it in the context of movement architecture and complications. A straightforward time-only automatic needs roughly 25 jewels for optimal implementation. A full calendar can legitimately require 30-35 jewels. 

Perpetual calendar complications can justify 40+ jewels. Numbers beyond what the movement's architecture logically requires suggest marketing considerations rather than engineering decisions.

At Tufina Watches, our approach is straightforward: every jewel serves a functional purpose. We don't pad jewel counts to inflate specification sheets. Bearing load calculations determine optimal jewel placement during movement development. If a friction point experiences significant wear or rotation, it gets a jewel bearing. If it doesn't, we don't add one just to bump up the numbers.

What Actually Separates Good Jewels from Bad Ones

Here's where things get interesting—and where most marketing materials go completely silent. Two movements with identical jewel counts can perform vastly differently based on jewel quality and installation precision. These factors rarely appear in specifications, yet they fundamentally determine bearing performance.

Jewel hardness consistency matters enormously. Lower-grade synthetic rubies sometimes exhibit hardness variations or internal stress points that accelerate wear. Premium jewel manufacturers maintain tight tolerances on material properties. The difference becomes apparent only after years of operation, when inferior jewels show measurable wear while quality bearings remain pristine. This is one reason why buying from established manufacturers with reputations to maintain pays off in the long run.

Hole diameter precision affects bearing performance directly and immediately. The pivot should fit the jewel hole with minimal clearance, typically 0.002 to 0.005 millimeters. Too loose creates positional variations that affect accuracy. Too tight increases friction and risks binding. 

Achieving optimal clearances requires precision boring and polishing of jewel holes to exacting tolerances. Cutting corners here saves maybe a dollar per movement but compromises performance for the watch's entire service life.

Jewel surface finish determines friction levels and oil retention. Premium jewels receive extensive polishing that creates mirror-smooth bearing surfaces. Lesser jewels might show microscopic roughness visible under magnification. This roughness increases friction and creates sites where oil breaks down faster. The polishing quality directly impacts how long the movement runs smoothly between service appointments.

Setting security ensures jewels remain properly positioned throughout the watch's life. Quality movements press-fit jewels into precisely machined recesses or secure them with specialized settings. 

Poorly secured jewels can shift microscopically, creating timing variations that seem mysterious until a watchmaker discovers the real cause. Examining jewel settings under magnification reveals a lot—gaps around jewel circumferences indicate quality compromises.

Some movements feature shock protection systems for the balance staff jewels. These spring-mounted jewel assemblies allow limited movement during impacts, preventing pivot damage when you accidentally knock your watch against something. 

Quality shock systems like Incabloc add complexity but dramatically improve durability. Implementation quality varies widely. Premium shock systems show precise spring tension and jewel alignment, while cheap versions might as well not be there.

Even jewel-bearing geometry affects performance in sophisticated ways. The jewel hole's internal shape—whether straight-walled or slightly conical—influences how oil distributes. End stone contours affect capillary oil retention. 

Tufina Theorema Sahara GM-119-3 Gold - Skeleton Mechanical Watch.

What Quality Bearings Mean for Long-Term Ownership

Properly implemented jewel bearings fundamentally determine how your mechanical watch performs over decades of ownership. The bearing quality affects everything from immediate accuracy to whether the watch remains serviceable thirty years from now.

Friction reduction through jewel bearings directly impacts power reserve. Metal bearings consume more mainspring energy through friction, reducing how long the watch runs between windings. Quality jewel bearings maximize power transmission efficiency, enabling longer power reserves from equivalent mainspring energy storage. This is why two movements with similar mainspring sizes can deliver dramatically different power reserves.

Wear resistance ensures timing accuracy remains stable over the years. Metal bearings gradually enlarge as pivots erode bearing surfaces. This wear creates play that allows pivots to shift position, introducing timing variations that worsen over time. Jewel bearings' hardness prevents measurable wear even after decades of operation. A well-maintained mechanical watch with quality jewel bearings can maintain accuracy specs for generations.

Lubrication retention in jewel bearings extends service intervals significantly. The smooth jewel surface holds oil effectively while minimizing lubricant degradation. Metal bearings absorb lubricants and accelerate oil breakdown through catalytic reactions with the metal surfaces. This difference affects how frequently your movement requires professional servicing—and service costs add up over a lifetime of ownership.

Service complexity decreases with quality jewel implementations. Watchmakers can clean and re-lubricate jewel bearings without replacement in most cases. Metal bearings often require rebushing—drilling out worn holes and installing new bushings—which adds significant service time and cost. The cumulative savings over decades become substantial.

Movement value retention correlates with bearing quality. Collectors recognize movements with comprehensive jewelry and quality implementation. Watches requiring bearing replacement or extensive rebushing lose value. Those maintaining original jewel bearings in good condition command premiums in the secondary market.

The bearing system represents one area where initial quality investment pays dividends throughout ownership. Movements with inferior jeweling cost less initially but require more frequent servicing and lose accuracy faster. Quality jewel bearings cost incrementally more during manufacturing but deliver vastly superior lifetime value.

How To Recognize Quality When You See It

Evaluating jewel bearing quality ideally requires access to the movement under magnification. However, certain indicators help assess implementation quality even without specialized equipment.

If the watch has an exhibition caseback, examine visible jewels carefully. Quality jewels appear perfectly circular with consistent color and clarity. The jewel settings should sit flush with the surrounding movement material. Gaps or uneven seating suggest rushed assembly or tolerance problems.

Observe rotor motion in automatic movements. Smooth, consistent rotation without wobble indicates proper jewel bearing implementation in the rotor system. Choppy rotation or visible eccentricity suggests bearing problems, either jewel misalignment or inadequate lubrication.

Listen to the movement's sound. Quality jeweled bearings produce subtle, consistent ticking. Scratchy sounds or irregular ticking patterns can indicate bearing friction or poor jewel implementation. While not definitive, unusual sounds warrant closer inspection.

Check timing accuracy across different positions. Place the watch dial-up, crown-up, crown-down, and on each side overnight. Timing should remain relatively consistent across positions. Significant positional variations often trace to bearing problems.