Large jade bi of this rich green color appear to be quite rare. One of smaller size (22 cm. diam.) is illustrated by J. Rawson, Chinese Jade from the Neolithic to the Qing, British Museum, 1995, p. 155, no. 7:6, where the author ascribes it to northwest China, c. 2000-1000 BC. As with the present bi it retains its cutting line on one side and is also somewhat translucent.