Identification and analysis of gemstone binding materials on imperial rank belts excavated from the tomb of Murongzhi

This paper analyzes and identifies the binders used in the jewel settings of the Baodian and Diexie belts excavated from the tomb of Murongzhi in Wuwei, Gansu, China. Fourier transform infrared spectroscopy (FTIR) indicated the presence of protein in the binder samples. The result of gas chromatography–mass spectrometry (GC-MS) shows that samples from both contained hydroxyproline, a characteristic amino acid for animal glue. Principal component analysis was performed on one of the samples, and it was concluded that the binder was a mixture of hide glue and egg glue. Further analysis using scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) and laser Raman spectroscopy (Raman) found that a red particulate matter visually identified in the binder was cinnabar, which was apparently added to binder in order to modify the color of the jewels. This study provides a basis for the conservation and restoration of future finds of elite jewelry. It also shows how imperial jewelry was made during the Tang Dynasty. Finally, the analysis of these heraldic belts provides a key insight the life and role of an exiled prince in the Tang court.