Glossary · Mechanism
Cap jewel
A flat jewel closing the end of a pivot hole to control endshake and hold oil.
Explanation
A cap jewel (endstone) is a flat jewel closing the end of a pivot hole. It controls the pivot's endshake and, with the hole jewel, forms an oil-retaining pair. Cap jewels are standard on balance pivots and appear on the fastest train pivots in higher grades. Shock-protection systems such as Incabloc and Kif are built around the balance's cap jewel assembly.
In the object catalogue
Catalogued objects whose own source record mentions “Cap jewel”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.
