China blue-and-white porcelain emerged in the Yuan Dynasty. The inkstone is considered as a Yuan Dynasty inkstone partly because of the design and the color of the patterns. In view of the quality of the blue-and-white patterns, this may be an imitation at later times. The temperature of winter in the northern area was below o degrees and water would freeze. Therefore, the heat-trapping design was popular. This inkstone has a square opening, which is easier for adding warm water into the inkstone to prevent the ink from freezing. The applied cover can also preserve heat.