In a recent study published in the journal AIP Advances, researchers used molecular and elemental spectroscopic techniques, such as laser-induced breakdown spectroscopy (LIBS), Raman spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy, to characterize silicate gems found in ancient Egyptian mines (1).
Colorful Gemstones placed on white reflection background, 3d rendering. | Image Credit: © sarawut795 - stock.adobe.com
For this study, the researchers examined a wide variety of gems, dating back to the era of the pharaohs. The team analyzed gem samples including peridot, beryl/emerald, amazonite, and amethyst to learn more about their chemical compositions. Doing so allowed the researchers to gain additional insight into ancient Egyptian history, which could potentially help determine trade routes in ancient civilizations (1). The researchers compared the gems to a sample of peridot uncovered in the Harrat Kishb lava field in western Saudi Arabia (1).
Jabal Umm aḑ Ḑulū volcanic crater in Harrat Kishb, Makkah Province, Saudi Arabia | Image Credit: © Walter_D - stock.adobe.com
Gems are valuable artifacts in archaeology. Gemstones have great historical and cultural significance. By uncovering ancient gemstones, archaeologists can use them to piece together what an ancient society might have been like, and what the people living during that time valued. These artifacts embody both cultural significance and visual beauty. However, it can be challenging to find an effective and efficient detection method that can distinguish between natural and synthetic gemstones (1). Spectroscopic techniques can be helpful in this process.
For example, LIBS is an effective technique that can distinguish different gem groups. By analyzing specific spectral windows, researchers identified unique characterizing elements for each gem variety. Raman and FT-IR spectroscopy also served as invaluable tools, offering distinct molecular fingerprints that can indicate potential alterations over time. FT-IR even unveiled specific functional groups responsible for the captivating colors seen in these gemstones.
In this study, three experimental methods were used, one for each spectroscopic technique. The experimental setup for LIBS analysis involved using a Q-switched Nd:YAG laser at a wavelength of 1064 nm. An Escelle spectrometer was coupled to an ICCD camera, and LIBS software was used to analyze the LIBS spectra (1). FT-IR analysis was conducted using a Model 4100 Jasco spectrometer working in the vibrational range of 400–4000 cm-1 wavenumber, using potassium bromide as a reference. Raman analysis was conducted with using a German-made confocal Raman microscope under the conditions of 473/532/633 nm laser excitation, z-focus, and a software-controlled x–y sample stage for line scanning and mapping (1).
Gem enthusiasts, historians, and gemstone traders stand to benefit from the ability to trace the origin and authenticity of gemstones, offering a tantalizing glimpse into the ancient past.
(1) Khedr, A. A.; Surour, A. A.; El-Hussein, A.; Abdelhamid, M. Characterization and discrimination of some gem silicate minerals adopting LIBS, FTIR, and Raman spectroscopic techniques. AIP Advances 2023, 13, 085101. DOI: 10.1063/5.0157623
New Study Explores Micro-Raman and FT-IR Analysis of Early Human Tools
June 16th 2025Researchers from Ca’ Foscari University of Venice and the University of Padua have uncovered the earliest direct evidence of Upper Palaeolithic humans deliberately processing the non-edible plant Isatis tinctoria, revealing complex behaviors involving medicinal or dye-related plant use over 32,000 years ago.
Short Tutorial: Complex-Valued Chemometrics for Composition Analysis
June 16th 2025In this tutorial, Thomas G. Mayerhöfer and Jürgen Popp introduce complex-valued chemometrics as a more physically grounded alternative to traditional intensity-based spectroscopy measurement methods. By incorporating both the real and imaginary parts of the complex refractive index of a sample, this approach preserves phase information and improves linearity with sample analyte concentration. The result is more robust and interpretable multivariate models, especially in systems affected by nonlinear effects or strong solvent and analyte interactions.
Laser Ablation Molecular Isotopic Spectrometry: A New Dimension of LIBS
July 5th 2012Part of a new podcast series presented in collaboration with the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS), in connection with SciX 2012 — the Great Scientific Exchange, the North American conference (39th Annual) of FACSS.
Bruce R. Kowalski: The Maverick Mind Behind Chemometrics
June 2nd 2025In this Icons of Spectroscopy article, Executive Editor Jerome Workman Jr. delves into the life and impact of Bruce Kowalski, an analytical chemist whose major contributions to chemometrics helped establish the field of applying advanced quantitative and qualitative mathematics to extract meaningful chemical information from complex datasets. Kowalski’s visionary approach to chemical data analysis, education, and software development has transformed the landscape of modern analytical chemistry for academia and industry.