Bluish-white-glazed Sixi melon edge jar of Song Dynasty

It is 14.2 cm in height, 18.7 cm in diameter, 7.2 cm in foot diameter and 0.51 kg in weight. The jar has a straight mouth, contracted neck, broad shoulder, round belly with melon edge, and slightly spreading short ring feet. Four ring systems are placed evenly on the shoulder. The whole body is covered in bluish-white glaze.