Note: Starting from the early Northern Song dynasty, kilns at Jingdezhen achieved success in producing very fine white-bodied porcelain covered with an illuminous glaze of icy blue tinge, earning the name qingbai, 'blue white', or yingqing, 'shadow blue'. The exquisite quality of qingbai porcelain was widely recognised, and the Southern Song ceramic historian Jiang Qi mentioned in his treatise Tao ji (Ceramic Records) that white porcelain produced at Jingdezhen was so refined and pure that it was known as Raoyu, 'jade of Rao'. Raozhou was the name of the region in which the Jingdezhen kilns were located.

Christie’s. Important Chinese Ceramics and Works of Art, Hong Kong, 26 November 2014