1 inch in diameter by 1 1/8 inches tall.Chinese seals are stamps made of bronze, gold, silver, jade, ivory, wood or stone, used as a sign of rank for government officials and for the authentication of documents or works of art. Xi was the term used for all seals before the Qin period (221–206 BC). After that the word applied to imperial seals only; other seals were called yin. In 104 BC the term zhang came into use for official seals. Today the term commonly used for any seal is a combination: yinzhangDuring the Qing period the Hui school had such prominent members as the epigraphist, poet and painter Cheng Sui (1605–91) and the art collector Ba Weizu (1744–95). These two master carvers and their fellow artists Wang Zhaolong (1722–80) and Hu Tang (1759–1826) were known under the name Xi si zi (The Four from the Xi region). The hallmark of their style was a technique called sedao (‘rough knife’), in which the cut lines were not smooth and even but of a pulsating roughness. This not only gave the seal legend an archaic flavour but also opened up new possibilities for artistic expression.At the beginning of the 18th century another school of seal-carving, the Zhe pai (Zhejiang school), emerged. The founder of this school was the scholar–artist Ding Jing (1696–1765). Like the members of the Hui school, followers of this school took Qin and Han seals as their ideal, but rather than emphasizing the strength and roughness of these seals, they tried to combine elegant lines with a lively tension between them. They also explored new possibilities in the spacing of characters, and the seals show a keen awareness of the balance between dense and sparse areas. Among the followers of Ding Jing were Jiang Ren (1743–95), Huang Yi (1744–1802) and Xi Gang (1746–1803) who, together with their master, were known as Xiling si jia (The Four from the Xiling region). The group was later extended to form the Xiling ba dajia (The Eight Great Artists of the Xiling region) and included the younger seal artists Chen Yuzhong (1762–1806), Chen Hongshou, Zhao Zhichen (1781–1852) and Qian Song (1818–60).At the beginning of the 20th century a group of literati founded the Xiling yin she (Xiling Association of Seal-carvers) at Hangzhou in Zhejiang Province. Its premises, centred around an old imperial summer villa, serve as a museum for the history of seal-carving, and exhibitions of modern seal-carvers’ works are held there regularly. Seal-carving is very much alive and is taught at academies of fine art. National exhibitions that feature the works of representative artists from each Chinese province are held annually, as young artists explore new forms of expression in this ancient art. There are very few seal collections in museums in the West. The major collections are in the Palace Museum and Historical Museum in Beijing, the National Palace Museum and the National Museum of History in Taipei, the Fujii Yurinkan Museum and the Sonoda private collection in Kyoto and the Neiraku Art Museum in Nara.