Compare with a related dragon-handled octagonal cup in the Qing Court Collection, illustrated in Jadeware (II), The Complete Collection of Treasures of the Palace Museum, Hong Kong, 1995, p. 246. pl. 190. See also a six-lobed jade washer with a Xuanhe mark dating to the Ming dynasty, illustrated in Gems of Beijing Cultural Relics Series - Jades, Beijing, 2002, p. 157, pls. 165-166.
The Zigang mark is after Lu Zigang, the renowned jade carver active in Suzhou in the second half of the 16th century. Details of his life and career are recorded by Zhou Nanquan, Gugong shuangyue kan, 17, no. 1, who states that Lu was a native of Taicang, Jiangsu province. Lu Zigang was one of the few Ming craftsmen of sufficient renown that his name was recorded in contemporary texts. His works were referred to by the Ming scholar Wang Shizhen, and they reportedly doubled in value on rumours that they were being collected inside the Imperial Palace.