Qing court necklaces were an essential part of court dress, indicating both rank and seasons, with different gemstones required for different ceremonies. The materials and form of the mandarin court necklace were strictly codified in the Qing Huidian Tukao, written in the early Qing dynasty, and also in the Huangchao Liqi Tushi, which was revised during the thirty-first year of Qianlong (1766). Cf. a court necklace with amethyst, pink tourmaline and coral beads, included in the joint exhibition, Secret World of the Forbidden City, The Bowers Museum of Cultural Art, California, and the Beijing Palace Museum, 2000, illustrated in the Catalogue, p. 72, where the author provides instructions on how to wear the necklace.