The Hearts of the Machine Why Are There Rubies Inside Your Mechanical Watch

The Captivating Red Glow

When you gaze through the sapphire crystal of a skeleton watch, your eyes are immediately drawn to the hypnotic rhythm of the balance wheel. But look closer, and you’ll notice tiny, translucent crimson dots scattered across the bridges and plates.

These are not merely decorative gems; they are the "silent heroes" of horology. Known as Watch Jewels, these rubies are essential to the precision and longevity of your mechanical timepiece.

What Exactly Are These "Rubies"?

In the early days of watchmaking, natural rubies were used. Today, most mechanical watches use synthetic sapphires or rubies, created in a lab to achieve perfect structural uniformity. They have the same physical properties as natural gemstones—ranking 9 on the Mohs scale (just below diamond)—making them incredibly hard and wear-resistant.

Why Does a Watch Need Jewels?

A mechanical watch is a miniature city of rotating gears. To keep time accurately, these gears must spin with as little resistance as possible.

• Reducing Friction: Metal-on-metal contact creates friction, which leads to heat and wear. By placing a polished ruby at the pivot points (the "axles" of the gears), watchmakers reduce friction to near zero.

• Protecting the Movement: Without jewels, the steel pivots would eventually grind away the brass plates of the movement, leading to mechanical failure. Rubies act as indestructible bearings that can last for decades, if not centuries.

• Oil Retention: Many jewels are shaped like tiny bowls (called "cup jewels") to hold microscopic drops of specialized lubricant, ensuring the movement stays smooth between services.

Does "More Jewels" Mean a "Better Watch"?

You might see "21 Jewels" or "25 Jewels" engraved on a movement. While a higher jewel count often indicates a more complex movement (like a chronograph or a perpetual calendar), it isn't a simple "more is better" contest.

For a standard time-only mechanical watch, 17 to 21 jewels is the "Golden Standard" for optimal performance. Anything more usually serves specific complicated functions rather than just basic quality.

The Aesthetic of the Skeleton Watch

For owners of skeletonized timepieces, the rubies serve an additional purpose: Visual Contrast. The deep red of the jewels against the silver or gold-toned gears creates a stunning "living" mosaic. In a skeleton watch, you aren't just buying a tool to tell time; you are buying a gallery of mechanical art where every ruby marks a crucial intersection of energy and motion.

Conclusion

The next time you admire your skeleton watch, remember that those tiny red dots are doing the heavy lifting. They ensure that your "mechanical heart" beats with precision, day after day.

Ready to see the inner workings for yourself? Browse our curated collection of Skeleton Mechanical Watches and witness the brilliance of horological engineering.