With its elegant fluid shape, lustrous blue-black glaze, and exceptional russet markings, this is a particularly beautiful vessel. Probably inspired by "hare's-fur" markings on Chien-ware tea bowls, potters of certain Tz'u-chou kilns in North China had begun by the eleventh century to decorate their black-glazed wares with russet-colored flecks and splashes. Such markings were created by applying an iron-oxide-bearing slip to the vessel surface. Some markings were splashed on the surface and others were created by dipping the vessel in the iron-saturated compound.