A Creamy and Black Jade 'Chilong' Bi Disc, Yuan/Ming Dynasty, 13th-16th Century元/明 青玉带灰皮双螭纹璧One side worked in raised relief with two chilong dragons, the other side with archaistic taotie masks and patterns in low relief, length 1.9 in — 4.9 cmProvenance:From a Private San Francisco Collection来源：旧金山私人珍藏Note:Compare with similar examples sold at Sotheby's Hong Kong, May 29, 2019, lot 610; and Bonhams Hong Kong, November 24, 2013, lot 274类似一例请参考香港苏富比，2019年5月29日，拍品编号610；以及香港邦瀚斯2013年11月24日，拍品编号274Estimate: $500—800