Blue-and-white porcelain is a kind of famous underglaze color porcelain in Chinese ceramic history. However, during the same period, blue-and-white porcelain exhibited different tones and “color dispersion” distances, such as during the Zhengde period. Energy Dispersive X-Ray Fluorescence (EDXRF), colorimetry, Optical Microscope (OM), etc, were used to study on the blue-and-white porcelain from the Hongzhi, Zhengde and Jiajing imperial kiln of Ming Dynasty. The results show that the cobalt-blue pigment of Zhengde imperial Kiln can be divided into three stages. The early years of Zhengde were similar to those of Hongzhi period, the blue-and-white porcelain showed blue tone due to use “Pingdengqing” cobalt-blue pigment with high Mn, low Co and high Al₂O₃ contents, “color dispersion” distance about 100 μm. In the middle period of Zhengde, the blue-and-white porcelain showed gray blue tone due to use “Shiziqing” cobalt-blue pigment with higher Mn, lower Co and similar Al₂O₃ content, compared with that of “Pingdengqing” cobalt-blue pigment, “color dispersion” distance about 100 μm. The later period of Zhengde was similar to the period of Jiajing, blue-and-white porcelain showed vivid slightly purplish-blue tone due to use “Huiqing” cobalt-blue pigment with low Mn, high Co and low Al₂O₃ contents, “color dispersion” distance about 180~650 μm. It can be known from archaeological experiments that the “color dispersion” distance and the crystal structure of the interaction layer of blue-and-white porcelain can be used to infer the content of Al₂O₃ in blue pigment. The experimental results enrich the historical documents of cobalt-blue pigment of Zhengde imperial Kiln in Ming Dynasty.

Keywords: Blue-and-white porcelain, Color dispersion, Co-spinel crystal, Cobalt-blue pigment.