Jewel

Definition

A synthetic ruby set where a steel pivot turns, so that the pivot runs on a hard, smooth surface that holds oil and does not wear. The jewel count on a spec sheet is a count of those bearings, and it maps how much mechanism a movement contains rather than how good it is. A hand-wound time-only movement needs about 17, as the Unitas-based Panerai OP II records; an automatic three-hander sits in the low 30s, the Rolex 3135 at 31; a column-wheel chronograph climbs to the 40s and 50s, the Breitling B01 at 47 and the Omega 9300 at 54; and a modular chronograph counts both its base and its module, which is why the Audemars Piguet 3126/3840 records 59. In this library the counts run from 3 to 117.