Greek keys are geometric meanders which were used in ancient Greece as a border decoration. When designed in a repetitive pattern it is also referred to as "running dog"". The use of this motif was revived from about 1800 during the Greek revival (or "Hellenism").
Victorian Scottish Agate Bracelet Designed with a Greek Key Pattern of Multicolored Agate Inlay.
Photo Courtesy of Lang Antiques.