Dish, 960-1279, 1 x 5 1/2 in. (2.54 x 13.97 cm), Guan ware Stoneware with pale blue glaze and induced crackle, China, 10th-13th century, Among the most rare of all Chinese ceramics, Guan ware vessels are generally small, simple and unadorned, reflecting the subtle artistic taste of the Southern Song (1127-1279) court that sponsored them. Made in Hangzhou, these pieces are characterized by their simple potting and thick glaze applied in so many layers that the glaze is often thicker than the body itself. The overall crackle pattern is caused by differences in cooling rates between the body and glaze. At first, the cracks were likely accidental, but they came to be widely appreciated and the effect was deliberately induced. This dish, possibly used as a scholar's brush washer, is distinguished by its rare shape and jade-like pale blue glaze. The copper rim protector was likely added during the Ming period.