A rare white jade armillary three-ring disc. Qing dynasty, Qianlong period. Photo Sotheby's

deftly carved from a single piece of jade with three interlinked movable rings mounted like a gyroscope with each ring moving on a separate axis, the innermost ring decorated on each side in low relief with the constellation of seven stars of the Big Dipper, opposite to the moon, all surrounded by swirling clouds, the middle ring similarly carved with stylised archaistic dragons, encircled by the outermost ring with rocks rising from cresting waves, the translucent stone of an even milky-white tone with natural veining; 11.6 cm., 4 5/8 in. Estimate 1,200,000—1,500,000 HKD. Lot Sold 2,420,000 HKD  (310,256 USD) to an Asian Private

NOTE: The present disc of rings is carved from flawless white jade, the luminosity of which is accentuated by the restrained shallow carving, and no other example appears to have been published. This piece appears to have been inspired by armillary spheres, a device that first appeared in China during the Han dynasty (206BC-AD220) to help understand the movements of the heavens. With Earth placed at the centre of orbit, the outermost ring, the meridian ring, was fixed in the north-south direction; the middle ring, the equatorial ring, was aligned to the earth's equatorial plane; and the innermost ring, the Chijing ring, had a sighting tube and could revolve around the single metal axis which was oriented to the North and South Poles. To use the armillary, the position of a star would be identified by pointing the sighting tube at it and reading the angles of the different rings.

The four mountains on the meridian ring represent symbols and directions from the I Ching (Book of Changes), a compilation of writings and beliefs that predate the Xia dynasty. The inclusion of the symbols on the armillary and the constellations on the innermost ring shows the close ties between the traditions of astrology and astronomy in China.

It was not unusual to find armillary spheres made of precious materials as objects d'art for the collection of the imperial court, which could be purely decorative or functional.

Sotheby's. Vestiges from China's Imperial History, 08 Apr 11, Hong Kong www.sothebys.com