Songhua stone from Qilin province is highly regarded for its qualities in the grinding of ink. These qualities were not fully appreciated until the Kangxi period, when due to the influence of the emperor, it began to be used in the making of inkstones. From the Kangxi period through the Qianlong period it was one of the preferred stones used for inkstones. A Songhua rectangular inkstone with similarly carved well and an eight-character inscription and seal on the reverse, in the National Palace Museum, is illustrated in A Special Exhibition of Sunghua Inkstone, Taipei, 1993, no. 16, p. 80. Of slightly smaller size (13.4 cm. long), it is dated to the Kangxi period. Another inkstone with pomegranate-shaped well, no. 14, p. 76, also dated to the Kangxi period, has the same square seal and a similar circular seal with an inscription flanked by dragons.