A type of finger ring that has a miniature watch set in the bezel. Some have a hinged crystal lid, and in one rare example from Augsburg, c. 1580, the movement is also hinged to fold within the bezel, and the hinged lid is in the form of a triptych. The watch sometimes has, in addition to the main dial, a second dial and a date dial.
Watch rings were made in the 17th century in Germany and 18th century in England (some by John Arnold, 1730-99, the celebrated horologist), France, and Switzerland; some are inscribed with the name of the maker of the watch. Such watches are being made today, usually as luxury articles with decoration of gemstones; some have a hinged jewelled lid to conceal the dial.
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson