"Ice crack", also known as cracked porcelain, is a variety of ancient Longquan celadon. It is named because its stripes are as broken as ice and its lobes are layered on top of each other, which has a three-dimensional effect. Among all kinds of glaze cracks in Ge kiln, "ice crack" ranks first, and it is known as "the character of Ge kiln, with ice crack as the top". Because of its unique cracking in the firing process, it shows infinite natural beauty. Unfortunately, after the Song Dynasty, the process of firing "ice cracks" was lost.