It is said that coloured glaze was firstly discovered by Gan Jiang in Chunqiu Zhanguo Times when he made the sword of the King. It is smelted by raging fire, which is the climax that nature would possibly bring. Coloured glaze, bullion, jade, china and bronze and name the Five Famous Ware of China. Yuan Zhen, a poet of Tang Dynasty, praises the charming, splendid and elegant demeanour of coloured glaze in his famous poem Coloured Glaze Song.