Jewel Count Marking — What This Mark Means
A marking indicating the number of jewels (synthetic rubies) used as bearings in the movement. This number reflects movement complexity but is not a direct indicator of quality.
What This Usually Means
Jewels in watch movements are synthetic ruby bearings placed at friction points to reduce wear and improve longevity. A basic mechanical movement typically has 17 jewels, while more complex movements with additional complications use more. The jewel count gives insight into the movement's construction complexity.
Where to Find It
Usually engraved on the movement itself, visible through an exhibition case back or when the case back is removed. It commonly reads "21 JEWELS," "24J," or similar. Some case backs also display this information.
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Common Variations
Common counts include 17 jewels (basic manual-wind), 21 jewels (standard automatic), 23-24 jewels (automatic with day/date), and 25+ jewels for chronographs and complex movements. Quartz watches may have 0-3 jewels.
Common Misconceptions
More jewels doesn't automatically mean better quality. Beyond the functional jewels needed for the movement design, additional "non-functional" jewels were historically added as a marketing gimmick. A well-finished 21-jewel movement can outperform a poorly-finished 25-jewel one.
What to Do Next
Use the jewel count alongside the caliber number to understand your movement. If the jewel count seems unusually high for the movement type, research whether all jewels are functional. This marking can also help identify the movement if the caliber number is missing.
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Related Markings
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Regulation MarkingMarkings on or near the movement's regulator indicating adjustment positions for timing accuracy. These are used by watc
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Frequently asked questions
Do more jewels mean a better watch?
Not necessarily. The jewels must be functional to add value. A standard automatic needs about 21 jewels; more than that requires corresponding complications to be useful.
What are watch jewels made of?
Synthetic rubies (corundum). They're used as bearings at friction points because they're extremely hard and reduce wear.
Why do quartz watches have fewer jewels?
Quartz movements have far fewer moving parts than mechanical movements, requiring fewer bearing points and thus fewer jewels.
What does '21 Jewels' mean on my Seiko?
It indicates the movement has 21 synthetic ruby bearings, which is standard for most Seiko automatic movements.
Can jewels be added to a movement?
Not practically. The jewel count is determined by the movement's design and engineering, not something added after manufacturing.
How many jewels does a typical automatic watch have?
Most standard automatic movements have 21 to 24 jewels. Chronographs and complex complications may have 25 or more.