The austere shape, imposing mass, and monumental proportions identify this perforated disk (bi) as an important ceremonial object of China's Neolithic culture. Worked from a mottled green stone identified as nephrite (a form of jade), it bears traces of saw and drill marks on its otherwise smooth surface that provide a textbook study of early Chinese lapidary techniques. The disk belongs to the late Neolithic Liangzhu culture of Jiangsu and Zhejiang provinces. In 1982, twenty-five such disks, ranging in size from five to ten inches in diameter, were excavated from a Liangzhu tomb near Changzhou, Jiangsu. Carbon-14 datings for the tomb place it between 2700 and 2200 B.C. The function and meaning of these disks are unknown. As late as the Han dynasty (206 B.C.-A.D. 220), jade disks performed a ritual function in aristocratic burials, where they were placed above the head, below the feet, and on the chest of the deceased. They were also depicted on painted burial shrouds of the second century B.C. In these paintings two dragons thread their way through a jade disk, going on their way from the nether world to the celestial realm. This suggests that jade disks may have been intended to help the deceased's soul in its journey to heaven. Although it is not certain that the disks functioned in this way in Neolithic times, the enormous labor involved in perfecting their abstract shape and lustrous finish is striking testimony to the reverence accorded them.