Watchmakers Rely on Synthetic Rubies for Precision Timekeeping

Have you ever wondered why mechanical watches contain varying numbers of small "rubies"? While they might appear decorative, these synthetic gemstones serve a crucial technical purpose in horology.

When watchmakers refer to "jewels" in a movement, they're typically describing synthetic ruby bearings—more accurately known as synthetic corundum. These microscopic components function as pivot bearings within the mechanical movement, significantly reducing friction between moving parts.

The benefits of using synthetic ruby bearings in watchmaking are substantial:

• Precision enhancement: Reduced friction means less energy loss and smoother operation, directly improving timekeeping accuracy.
• Compact dimensions: Their miniature size allows for more efficient movement designs.
• Predictable friction coefficients: Provides consistent performance for precise engineering calculations.
• Temperature stability: Maintains consistent performance across varying environmental conditions.
• Maintenance-free longevity: Can operate without lubrication for decades, extending service intervals.

These watch components aren't mined gemstones but precision-engineered materials. Produced primarily from aluminum oxide with chromium oxide additives, they're created through high-temperature fusion and crystallization processes similar to the Verneuil method for synthetic sapphire production. Their industrial manufacturing makes them far more affordable than natural rubies.

The number of jewels in a mechanical watch directly correlates with movement complexity. A standard time-only watch typically contains 17 jewels, while complications like chronographs or perpetual calendars require additional bearings for their extra mechanisms.

These synthetic rubies serve critical mechanical functions:

• Friction reduction: Their primary purpose is minimizing energy loss between interacting components.
• Component support: They provide stable pivots for rotating elements within the movement.
• Wear resistance: Their exceptional hardness prevents premature degradation of moving parts.

During a recent visit to a Swiss watch manufacture, I attempted the delicate process of setting these microscopic rubies. Under magnification, using specialized tweezers, I first dropped a jewel, then launched one across the room, before finally placing one upside down in its intended position. This experience underscored how jewel setting—like all fine watchmaking—demands extraordinary patience, skill, and experience.

While synthetic rubies carry minimal intrinsic worth, their presence in watch movements represents horological craftsmanship. Each precisely placed jewel reflects the watchmaker's dedication to precision and longevity—qualities that define mechanical watchmaking at its finest.

• Alternative materials: Some manufacturers experiment with ceramics for bearings, though rubies remain industry standard.
• Color variations: Chromium oxide creates the characteristic red hue, but other colors exist for specialized applications.
• Shapes and applications: Typically round or oval to optimize installation and performance.
• Maintenance considerations: While jewels themselves require no lubrication, regular servicing maintains optimal movement performance.