Animated coloured scanning electron micrograph (SEM) of cogs and gears from a seven-jewelled watch escapement. The red area is a ruby jewel used in a bearing. An escapement is a device within a watch that provides periodic impulses to the balance wheel that helps to regulate time- keeping. Jewels (natural or man-made) were used in watch bearings because their smooth surfaces offer little friction and slow wearing. Due to the age of the watch there has been some corrosion of the metal gears.