Gemological and Spectroscopic Identification Characteristics of Frozen Jelly-Filled Turquoise and Its Raw Material
JIA Yu-ge1, YANG Ming-xing1, 2*, YOU Bo-ya1, YU Ke-ye1
1. Gemmological Institute, China University of Geosciences (Wuhan), Wuhan 430074, China
2. Gem Testing Center, China University of Geosciences (Wuhan), Wuhan 430074, China
Abstract：The organic filling treatment of turquoise has a long history, and there has been much research on two filling methods: immersion (acrylates) and injection (epoxy resins), while frozen jelly filling (acrylates) is a relatively new filling method with a weak research base. Using conventional gemological methods, FTIR, 3D fluorescence spectrometer and UV-VIS spectrum analysis, combined with the frozen jelly material used for the treatment, this paper presents a systematic comparative analysis of the gemological and spectroscopic characteristics of natural turquoise raw material and its corresponding frozen jelly-filled turquoise. The results showed that the color and density of turquoises were significantly enhanced by the frozen jelly filling, with glue residue and white “pine flower” on the surface; frozen jelly-filled turquoises showed weak-moderate blue fluorescence under the LW UV lamp and weak fluorescence under the SW, with obvious luminescence in the glue residue positions, while raw turquoises were inert under both LW and SW. The IR spectra of the frozen jelly solution showed CO stretching vibration peak [(1 722±5) cm-1], C—O stretching vibration peak [(1 156±5) cm-1], CC stretching vibration peak [(1 637±5) cm-1], benzene ring structure and C—OH absorption peaks, indicating that its composition may be a copolymer of compounds containing benzene ring, carboxylic acid, alcohol and other structures with methacrylate. The infrared spectrum of frozen jelly-filled turquoises showed the organic group vibrational peaks corresponding to the frozen jelly solution, effectively identifying filled turquoises from raw materials. 3D fluorescence spectra showed that raw turquoises did not appear obvious fluorescence centers throughout the excitation wavelength range, frozen jelly-filled turquoises all appeared characteristic fluorescence centers with emission wavelengths around 465, 445 and 410 nm, and excitation wavelengths in the range of 360～400 nm, corresponding to the fluorescence centers of the frozen jelly solution, indicating that the fluorescence was caused by glue, which can be taken as important evidence of frozen jelly filling. The UV-Vis absorption spectra of both raw turquoises and frozen jelly-filled turquoises were consistent with the characteristics of natural turquoises, indicating that no organic dyes were added during the jelly-filling process.
贾雨歌，杨明星，游博雅，余柯烨. 冻胶绿松石及其原料的宝石学与谱学鉴别[J]. 光谱学与光谱分析, 2023, 43(09): 2974-2982.
JIA Yu-ge, YANG Ming-xing, YOU Bo-ya, YU Ke-ye. Gemological and Spectroscopic Identification Characteristics of Frozen Jelly-Filled Turquoise and Its Raw Material. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(09): 2974-2982.
