Pi Disk

Pi Disk
Ch'i-chia Culture Style (ca. 2200-1800 B.C.)
Diameter: 21 cm, diameter of hole: 6.7 cm,
thickness: 0.73 cm

??This lustrous jade pi disk exhibits the distinct "sugar-brown and white" form of coloration, which is caused by high amounts of iron. From the inside out, the order of the coloring is; grayish green to dark brown to light brown (the original surface of the jade stone). One side slightly protrudes, and the light brown areas at the top and bottom are slightly thinner. The hole and rim were damaged in places and polished smooth.

??Both sides are engraved with cloud and mist patterns, which suggest that this disk was reworked in the Han dynasty (206 B.C.-A.D. 220). The rim was also engraved with an inscription by the Ch?ien-lung Emperor (r. 1736-1795).

??Pi disks with patterns of "sugar-brown and white" may have been deliberately chosen by the Ch'i-chia people in response to the appearance of, for example, the moon in an autumn evening. Or, perhaps they associated the colors of the sky with the natural coloring of the jade and thus attached a particular importance or belief to it.