1. Gemmological Institute, China University of Geosciences（Wuhan）, Wuhan 430074, China
2. Hubei Province Gem & Jewelry Engineering Technology Research Center, Wuhan 430074, China
3. School of Jewelry, West Yunnan University of Applied Sciences, Tengchong 679118, China
4. National Gems & Jewelry Testing Group Training Center, Beijing 102627, China
Abstract：The emeralds from Zambia, with high economic value, occupy an important position in the domestic jewelry market. In order to enrich the traceability information of emerald origin, a comprehensive test of emeralds from the Kagem mine in Zambia was conducted using conventional gemological identification instruments, combined with test and analysis methods such as laser Raman spectroscopy, laser exfoliation inductively coupled plasma mass spectroscopy, Fourier transforms infrared spectroscopy and UV-Vis-NIR spectroscopy, to study the gemological, chemical composition and spectroscopic characteristics of the Kagem emeralds and providing practical and effective methods for identifying the characteristics and origin tracing of the emeralds from the origin. The results show that the emerald samples from the Kagem mine ranged from green to blueish green. The refractive index was higher than other origins, and varied from 1.580 to 1.595. The emeralds from the Kagem mine were typically inert to long- and short-wave UV radiation. The emeralds showed no reaction under the Chelsea filter. Dichroism was medium yellowish green and bluish green. Magnified observation shows that the emeralds contained abundant solid-phase inclusions inside. The gas-liquid two-phase inclusions are mostly elliptical or flat strips, and the gas volume accounts for about one-third of the inclusions. Laser Raman spectroscopy shows that the tubular inclusions were actinolite, the black-brown metallic minerals were magnetite, the black irregular inclusions were carbonaceous, and the columnar inclusions were albite. The chemical composition of emeralds distinguishes Kagem from other areas of origin. Compared to other origins, Kagem emeralds exhibit chromogenic elements rich in Cr and poor in V. There are high Fe, high Mg and high alkali metal elements in Kagem emeralds. The infrared spectra show that the characteristic absorption peaks of type Ⅰ water in emeralds of this origin were mainly at 7 268 and 7 140 cm-1, and the characteristic absorption peaks of type Ⅱ water were mainly 7 075, 6 840, 5 340, 5 205, and 1 619 cm-1. The IR absorption peaks of type Ⅱ water were stronger than those of type Ⅰ water, indicating that the relative proportion of type Ⅱ water was greater than that of type Ⅰ water. This feature can be distinguished from the emerald with poor alkali. The UV-Vis-NIR absorption spectra of emeralds were related to Cr3+, Fe2+ and Fe3+, and the positions and intensities of the absorption peaks were different in different directions.
Key words：Kagem emerald; Chemical composition; Inclusion; Infrared spectrum
高 冉，陈全莉，任跃男，鲍珮瑾，黄惠臻. 赞比亚Kagem祖母绿的宝石学及谱学特征研究[J]. 光谱学与光谱分析, 2023, 43(10): 3186-3192.
GAO Ran, CHEN Quan-li, REN Yue-nan, BAO Pei-jin, HUANG Hui-zhen. Study on the Gemmological and Spectral Characteristics of Emeralds From Kagem, Zambia. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(10): 3186-3192.
