When you hear about the jewels in a watch, you might picture glittering stones set into the case. In horology, however, the phrase refers to tiny, highly specialised bearings that keep the movement running smoothly. These jewels are not for decoration. They are engineered, precision bearings—usually tiny synthetic rubies—embedded in the movement to reduce friction, minimise wear and enhance longevity. In this guide we explore what are the jewels in a watch, why they matter, where they sit in the mechanism, and what watch enthusiasts should know to understand the heartbeat of mechanical timepieces.
What Are the Jewels in a Watch? A Basic Explanation
What are the jewels in a watch? In simple terms, they are the bearing surfaces that support the pivots of the gear train and the critical components of the escapement. The purpose is to create exceptionally hard, smooth, low-friction contact points where metal parts would otherwise wear quickly. The traditional term “jewels” survives in modern watchmaking because the bearing concept was historically achieved with jewel stones—natural or synthetic. Today, virtually all mechanical watches use synthetic rubies (a form of corundum) as these bearing jewels.
These tiny gems sit at precise points inside the movement: they guide the rotation of wheels, anchor the escapement’s pallet fork, and support the balance wheel’s pivots. Rather than being decorative, they are functional, vital components. The result is improved accuracy, reduced maintenance intervals and a longer service life for the watch.
Why a jewel, rather than plain metal, in a bearing?
Jewel bearings minimise friction in two key ways. First, they provide a very hard, wear-resistant surface that resists scratching and deformation from repeated contact with steel pivots. Second, they can hold tiny quantities of oil in microscopic reservoirs, distributing lubricant directly to the moving interface. The combination of hardness, lubricity and precise geometry makes jewels an efficient solution for high-precision timekeeping.
The Origins of Jewelled Movements
The use of jewels in timepieces began in earnest as clockmakers sought to improve durability and accuracy. Early clocks relied on metal bearings that wore rapidly. The idea of using jewel bearings, especially rubies, emerged in the 18th and 19th centuries as a way to extend service intervals and keep time more reliably. With the advent of synthetic ruby production in the 20th century, watchmakers could place high-quality ruby bearings at numerous positions inside a movement without the limitations of naturally sourced stones.
Today, the concept is standard across most mechanical watches, from modest daily wearers to high-end luxury models. The exact number and placement of jewels vary by movement design, but the underlying principle remains the same: reduce friction, increase longevity, and preserve accuracy through stable, low-friction pivots and escapement interactions.
What Are the Jewels in a Watch Made Of? Synthetic Rubies and Corundum
The vast majority of jewels used in modern watches are synthetic rubies. Rubies and sapphires are both varieties of corundum, differing mainly in trace elements that give them distinct colours. In watchmaking, the term “ruby” is used generically to refer to synthetic corundum bearings, which are manufactured to the required hardness, clarity and stability for precision pivots.
How synthetic rubies are created
Synthetic rubies are produced using controlled crystallisation processes, most commonly the Verneuil process or the flux method. These techniques yield highly uniform, transparent stones with minimal inclusions. The result is a material with an hardness near 9 on the Mohs scale, exceptional scratch resistance and excellent wear properties. For watchmakers, this translates into bearings that retain their shape and smoothness across countless cycles.
The properties that matter for bearings
Beyond hardness, synthetic rubies used as jewels offer excellent dimensional stability, chemical inertness and a very smooth lubrication surface. Their optical clarity is less important than their mechanical properties, but it does mean that tiny rubies can be polished to mirror-like finishes. In practice, these jewels can be manufactured in two primary forms for movement use: cap jewels and hole jewels, each serving specific bearing functions within the gear train and escapement.
Where Are the Jewels Placed? Key Bearing Points in a Movement
In a mechanical movement, jewels are scatter-brained through the gear train, but they cluster at vital pivot points where wear would be most damaging. The arrangement is a carefully engineered map that keeps everything running with minimal resistance and maximum longevity.
The main pivots: balance staff, escape wheel and pallets
The balance wheel and its staff are the heartbeat of the watch’s timekeeping. The pivots there sit in jewel bearings to minimise friction as the balance swings. The escape wheel and pallet fork—the core of the escapement—also rely on jewel bearings to ensure precise lock and release with each beat. These parts interact at high speeds and with tiny tolerances; jewels keep the contact surfaces stable over time.
The centre, third and fourth wheels
The centre wheel, along with the third and fourth wheels, forms the primary gear train that transmits energy from the mainspring to the escapement. Each wheel is supported by at least one jewel bearing to reduce friction as it turns. In many designs you will find plain or cap jewels at these pivot points to cradle the respective shafts and maintain smooth rotation under varying loads.
Endstones and hole jewels
Two common forms of jewels are endstones (often called cap jewels) and hole jewels. Endstones support the end of a pivot, acting as a cap over the pivot’s top, while hole jewels encase the pivot in a jewel bearing with a drilled hole through which the pivot passes. Both configurations aim to minimise lateral play and reduce wear, keeping the pivot aligned and lubricated as it turns.
Jewel Count: How Many Do You Really Need?
Watch enthusiasts often ask, “How many jewels should a movement have?” The answer depends on the movement’s complexity and design. A simple, robust manual wind or automatic movement may operate well with around 17 to 21 jewels. More elaborate movements—especially those with additional complications such as a chronograph or perpetual calendar—often incorporate 23, 25, or more jewels to support extra gears and levers.
Typical jewel sets by movement type
– Basic three-hand movements (time, hours, minutes) often use 17 to 21 jewels.
– Movements with date functions typically add a few jewels for the calendar linkage.
– Chronograph-equipped movements commonly feature 20 to 25 jewels, with additional jewels dedicated to the chronograph gear train.
– High-end or highly complicated movements may exceed 25 jewels to cover extra mechanisms and resetting levers.
It’s important to note that a higher jewel count does not automatically guarantee better accuracy. The layout, quality of manufacturing, lubrication and overall design determine performance just as much as the number of jewels. In practice, the right balance of jewels and engineering results in reliable, smooth operation.
Do More Jewels Equal More Accuracy? Debunking the Myth about What Are the Jewels in a Watch
The common belief that more jewels make a watch more accurate is a simplification. While jewels reduce friction and wear, accuracy hinges on many factors: the precision of the gearing, the quality of the balance, the stability of the escapement, the effectiveness of lubrication, temperature compensation, and the overall rigidity of the movement architecture. A 17- to 21-jewel movement that is well designed and well maintained can be far more accurate than a higher-jewel piece with inferior manufacturing or inconsistent lubrication.
In short, jewel count is a useful indicator of complexity and the mechanical locations requiring low-friction bearing surfaces, but it is not a sole measure of precision. If you see a movement with 27 or more jewels, inquire about what those extra bearings do. They are often tied to calendar wheels, chronograph components or other complications rather than a direct increase in timing accuracy.
Identifying Jewels in a Movement: Practical Tips
For the curious, identifying how many jewels a movement uses can be enlightening, though it often requires expert disassembly or high-quality documentation. Here are practical pointers to understand what are the jewels in a watch without removing the movement yourself:
Look for movement specifications
Official specifications from the manufacturer or trusted reviews often state the jewel count and its distribution. This information is typically published for each calibre and can be found in official product literature or credible horology resources.
Ask about the main bearing points
When investigating, focus on the escapement, balance wheel pivots, the centre wheel, and the third and fourth wheels. These are the typical locations requiring jewel bearings. A higher-than-average count is usually indicative of additional complications rather than a straightforward improvement in core timekeeping.
Consider the movement’s age and design
Older, vintage movements may have lower jewel counts by modern standards. Contemporary or highly engineered calibres may have more jewels due to added features or refined manufacturing tolerances. Context matters when interpreting jewel counts.
Maintenance and Lubrication: How Jewels Interact with Oil
The life of the jewels is closely tied to lubrication. Jewels are designed to hold tiny reservoirs of oil, and the cap or hole bearing surfaces are finished to maintain a thin, consistent film of lubricant. Proper lubrication reduces friction, protects against metal-on-metal wear and helps maintain accuracy over time. It’s essential for watch owners to adhere to recommended service intervals, where a professional watchmaker will clean the movement, inspect jewel integrity, replace worn oil, and re-lubricate as needed.
Temperature, shock, and humidity can influence oil viscosity and the performance of jewel bearings. A well-maintained movement, kept away from strong magnetism and subjected to regular servicing, will preserve the lubrication geometry around the jewels and maintain stable performance for years.
Chronographs, Calendars and Extra Jewels: What Adds Up?
Movements with additional complications require more jewel bearings to support the increased mechanical workload. A chronograph, for instance, introduces extra gears and levers to measure elapsed time. Each added feature may require endstones and hole jewels at the new pivot points, along with jewels to stabilise the chronograph wheel train. A perpetual calendar introduces the day, date, month and leap-year mechanisms, often accompanied by more jewels to accommodate the calendar wheels and their interactions.
In practice, the extra jewels help maintain consistent operation under the extra demands of these complications. However, the presence of more jewels should be interpreted within the context of the movement’s architecture and the quality of craftsmanship rather than as a mere indicator of value.
Swiss vs Japanese Movements: Jewel Practices Across Regions
Across regions, jewel counts and configuration preferences differ due to design philosophies, manufacturing capabilities and traditions. Swiss movements have a long-standing reputation for high precision and meticulous finishing, frequently employing jewel-bearing arrangements that optimise performance for luxury timepieces. Japanese movements, especially from major producers, often emphasise reliability, ease of maintenance and efficiency, with jewel counts that align with robust, mass-produced calibres while still delivering excellent accuracy.
Examples include standard automatic movements with many jewels for durability, and specialised calibres with a focus on longevity and serviceability. Whether Swiss or Japanese, the core principle remains the same: jewel bearings provide stable, low-friction interfaces for pivotal components, enabling timekeeping that you can trust over long service intervals.
Care and Handling: How to Respect the Jewels in Your Watch
Proper care for your timepiece helps to protect the jewel bearings. Here are practical steps to respect the jewels day to day:
- Regular servicing by a qualified watchmaker, typically every 3–5 years for a standard mechanical watch.
- Avoid exposure to strong magnetic fields, which can affect the lubricants and timing.
- Keep the watch clean and dry; moisture can corrode metal parts and alter lubrication around jewel bearings.
- Store watches in a stable environment with moderate humidity and temperature to minimise lubricant changes.
- Be mindful of shocks; hard impacts can misalign pivots or damage jewel settings.
What Are the Jewels in a Watch: A Recap of Key Concepts
To recap concisely: what are the jewels in a watch? They are synthetic ruby bearings used in critical pivot points of the movement to reduce friction, wear and to improve longevity. They come in cap (endstone) and hole varieties and sit at pivot points across the gear train, including the escapement and balance wheel. Jewel counts vary by calibre, influenced by the presence of additional complications and movement architecture. While more jewels can support increased complexity, the highest quality timepieces achieve superb performance through careful design, precision manufacturing and proper maintenance rather than merely increasing the number of jewels.
In Practice: Understanding Your Watch’s Jewel System
When assessing a watch’s movement, you don’t need to be a Master Watchmaker to appreciate the role of jewels. Look for clarity in the movement’s design, smoothness of winding, and consistent timekeeping under normal wearing conditions. For enthusiasts, a deeper dive into the official calibre specifications will reveal the exact jewel count and the intended function of each bearing. This knowledge helps demystify a movement’s complexity and highlights the artistry behind seemingly simple timekeeping.
Key takeaways for what are the jewels in a watch
- Jewels are bearings, not decorations, used to reduce friction and wear.
- Most modern watches use synthetic rubies (corundum) as jewels.
- Jewels sit at pivotal points in the gear train and escapement to optimise performance.
- The jewel count reflects complexity and design choices, not simply accuracy.
- Regular servicing ensures lubricants stay effective around the jewels, preserving precision and longevity.
Conclusion: The Small Yet Mighty Jewels that Keep Time
What are the jewels in a watch? They are the small, mighty bearings that enable a timepiece to run with grace, precision and resilience. By serving as hard, low-friction surfaces for the pivots and escapement, these synthetic rubies help minimise wear, extend service intervals and sustain accurate timekeeping across years of use. Whether you wear a modest everyday watch or a sophisticated chronograph with many complications, the jewels inside are central to the movement’s performance and the watch’s enduring appeal. In the end, understanding the role of these tiny bearings deepens appreciation for the craft of horology and the quiet, precise mechanism that sits on your wrist.