Bluish-white-glazed ewer of Northern Song Dynasty

It is 21.3 cm in height, 6 cm in diameter, 7.9 cm in foot diameter and 0.56 kg in weight. It is shaped in straight mouth and square rim. The ewer has a long neck, oblique shoulder, round belly, and high ring foot. A slightly-curved long spout and a flat and curved handle is on either side of the shoulder. There are three string patterns on the shoulder and belly, and a circle of lotus pattern on the lower part of the belly. The whole body is covered with bluish-white glaze. An ewer is an ancient wine warming vessel.