This content was first published on IGR – Italian Gemological Review no. 19 in 2024. The information provided here is therefore current as of the original publication date.
Meiyu Shih (China University of Geosciences), along with two other researchers, Ye Yuan and Guanghai Shi, have developed a new method to discriminate the geographical origin of white-greenish nephrite jade, essential for accurately assessing its economic value.
The study has been published in the Journal of Analytical Atomic Spectrometry and utilized LIBS spectroscopy to analyze 364 samples from various locations including China, South Korea, and Russia. Four machine learning methods (LDA, SVM, PLS-DA, and RF) were employed, in addition to a system that combines the results of all methods to achieve a more accurate prediction. The results showed high precision, ranging from 94.01% to 100%. Certain spectral lines, such as those associated with trace elements like Fe, Mn, Al, Sr, Be, Li, Na, and K, played a significant role in discriminating between the multiple origins.
The study highlights the importance of considering the effects of the matrix, microstructure, and grain size variations in LIBS analysis. Despite limitations in the sensitivity detection for some elements, LIBS emerges as a promising technique for origin discrimination in various fields, including gem trade and archaeology.
These findings pave the way for further advancements in data processing methods, with potential applications extending beyond nephrite jade to include various gems and geological materials. The use of LIBS is increasingly emerging as a routine technique for origin analysis in gemological studies.
Notes:
(1) https://pubs.rsc.org/en/content/articlepdf/2024/ja/d3ja00464c
Gem news published on IGR – Italian Gemological Review #19 – Autumn 2024.
