Non-Invasive Identification of Blue-And-White Porcelain: Comparison of Vietnamese, Yunnan and Jingdezhen Wares Using Reasoned Visualization and PCA

The XRF, Raman, and fluorescence signatures of approximately fifteen blue-and-white and white porcelain sherds are compared. The assemblage comprises fourteenth- to sixteenth-century porcelain sherds, including Yuan and Ming wares from the Jingdezhen kiln sites, fifteenth- to sixteenth-century wares from the Yuxi and Jianshui kiln sites in Yunnan (China), and Vietnamese sherds comparable to ceramics recovered from the Cu Lao Cham (Hoi An) shipwreck preserved in private collections. Particular attention is paid to the XRF signals of impurities associated with sands (Zr, Y), fluxes (Rb, Sr), and cobalt-bearing ores (As, Mn, Fe, Ni, Bi), as well as to the Raman identification of specific phases in Chinese and Vietnamese porcelains. The similarity between Yunnan and Vietnamese blue-and-white wares is confirmed, notably by their high zirconium concentrations, whereas rubidium concentrations provide a means of distinguishing between the two regions. Overall, XRF signatures enable the non-invasive classification of the sherds according to their material characteristics. The resulting classifications are based on visualizations of clusters in the elemental compositional data using selected elements relevant to geological provenance and ceramic processing. These classifications are then compared with those obtained using PCA and hierarchical clustering based on Euclidean distances. Raman spectra highlight the presence of specific phases, including calcium silicates and phosphates. For the first time, particular emphasis is placed on the importance of considering the entire fluorescence spectrum as an identification tool. Special attention is given to the chromium fluorescence doublet with the α-alumina phase formed during the transformation from 2:1 mullite to 3:2 mullite at temperatures above 1200–1250 °C.