Jade Gangmao Amulet, Eastern Han Dynasty (25-220). Side length 1.2 cm, Height 2.5 cm © Shanghai Museum 

Jade gangmao (刚卯) and yanmao (严卯) were cuboid amulets with evil-exorcising verses inscribed on four faces. While gangmao and yanmao differed in inscription, they both served as an evil exorciser. The Eastern Han court required its officials and officers to wear a gangmao as an accessory to court attire, and jade gangmaos were worn exclusively by noblemen ranked marquis or above.