VERY RARE. The deeply rounded sides of this conical bowl rise gently from a circular foot toward an indented rim, covered overall with a silvery-blue haze. The glaze stops short of the unfinished foot in a neat bulge above the body. The ?silver gray? glaze is caused by a natural firing atmosphere and the crystallization of magnetic iron oxide on the glaze?s surface during cooling. A character or symbol is impressed in the center of the foot. Southern Song Dynasty