Also known as "Anonymous Son", it is produced in Jiangxi. "Records of Ruizhou County": "There is a nameless son in Tianzegang, shanggao county, and Jingdezhen paints porcelain"; "Zhengzitong": "The new black ochre in Luling. Grinding water to draw porcelain blank, colorless at first, burned all day blue. Jingdezhen takes Wuyuan, and the famous paintings burn green and are nameless. " Thick gray blue and white was fired in Zhengde in Ming Dynasty, and the color used was Shi Ziqing.