Geographic origin determination in emeralds from Colombia, Zambia, and Pakistan: photoluminescence analysis and correlation with trace elements

Determining an emerald's origin can be challenging due to the presence of crystals with similar physicochemical properties in different parts of the world. The analyses of the chemical composition of emeralds have become increasingly relevant in light of the diverse genetic environments in which they are found. However, discovering new deposits with comparable characteristics has prompted researchers to develop innovative techniques for determining their provenance. This publication presents the results of a photoluminescence analysis to differentiate Colombian emeralds from those from other parts of the world, specifically from Zambia and Pakistan. The study employed the wavelength position of R1 in 684 nm to achieve this differentiation. Furthermore, it allows for the differentiation between crystals of both Colombian emerald belts, utilising the R1 position at 683.65 nm and its intensity. Chemical analysis grants emeralds from both belts to be distinguished by the quantity of elements such as K, Cl, and Sc, as well as the ratio between chromophore elements (Cr/V). Finally, the low abundance of elements such as Fe, Ti, Cu, Zn, and Ni in Colombian emeralds compared with those from Zambia and Pakistan allows further differentiation among deposits.