New Methodology in Studying Amber Gemstones
A new methodology for the Amber characterization, combining the micro-ATR spectroscopy with ultraviolet (UV) fluorescence imaging, has been developed by GIG Research Department team in collaboration with GRS – GemResearch SwissLab, Peretti Museum Foundation and Foundation for Scientific Advancement (Arizona – USA). The IR spectra were analyzed on the basis of the differences observed in the samples by UV light exposure at Long- and ShortWaves (LW, SW). Indeed, amber exposed to UV light can be fluorescent, showing different colors and intensities, but a clear correlation between this phenomenon and origins, maturities, or treatments of the amber is nowadays under discussion. In this scenario, an analytical methodology developed for the tal quale sample characterization applicable to Burmese amber, as well as all other amber types, produces results particularly suitable for gemological laboratories and will expand the spectroscopic information on amber.
The efforts of the International Research Team have been rewarded with a scientific publication on peer-review Applied Spectroscopy journal (Jan2021, OnLineFirst – DOI 10.1177/0003702820986880)
Burmese Amber Compared Using Micro-Attenuated Total Reflection Infrared Spectroscopy and Ultraviolet Imaging
By M. Musa, T.G. Kaye, W. Bieri and A. Peretti
Attenuated Total Reflection (ATR) spectroscopy coupled with a microscope allows for the analysis of specimens without any preparation, spatially correlated with the morphology of the specimen. These characteristics make micro-ATR systems very useful for studying gemstones and in particular amber samples. Indeed, in this report, the micro-ATR technique was used to characterize three Burmite samples, as case studies. Particularly, focusing the ATR crystal spot on the amber surface where a difference in the Ultraviolet (UV) reaction was previously detected, thereby relative differences in the IR spectrum could be analyzed. Here we present a methodology combining the UV imaging technique with the micro- Attenuated total reflection Fourier transform infrared spectroscopy (micro-ATR/FT-IR) analyses, in order to correlate the fluorescence information with the molecular vibrational modes of amber and their relative spatial distribution.
Finally, this work is intended as an initial methodology study and part of the amber characterization project, focused on characterizing the Burmese amber collection of the Peretti Museum Foundation from several disciplines (i.e., palaeoentomology, vibrational spectroscopy, neutron tomography, etc.).