Study on Chemical Compositions and Infrared Absorption Spectra of Natural and Synthetic Emeralds

As a top-grade and rare gemstone, emerald is a variety of the mineral beryl with the chemical composition Be₃Al₂ (SiO₃)₆. It is a significant research project to identify natural emerald as opposed to synthetic emerald. The routine gemological methods, laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and Fourier Transform Infrared Spectroscopy (FTIR) absorption techniques were used to study natural emeralds from Colombia and Brazil and synthetic emeralds made by flux-grown and hydrothermal synthetic methods. The green color of emerald was closely related to the concentration of the trace element Cr (Ⅲ). The infrared absorption spectra characteristics indicated obvious differences between natural and synthetic emeralds. This technique can provide important information for identifying natural and synthetic emeralds, combined with the existing state of water and the absorption peak of chloric ion in emeralds. Chemical compositions obtained by LA-ICP-MS alone cannot differentiate between natural and synthetic emeralds. Therefore, combining the data with routine gemological methods, infrared absorption spectrum characteristics and inclusion characteristics are essential for distinguishing between natural and synthetic emeralds.