What are the “jewels” of a watch movement?
When a watch description lists the jewels, as in “17-jewel automatic movement”, it is referring to the gems used as bearings in the finished movement. The jewels are usually synthetic rubies, which are a harder substance than metal. The gears of a watch will wear down over time due to the constant friction caused by metal rubbing against metal. Watchmakers place the synthetic rubies on highly stressed parts to increase durability and keep the movement in alignment. Mechanical, automatic and a few quartz watches have jewels, and timepieces featuring extra complications like chronograph watches will have a higher number of jewels.
