Identification and characterization of gemstones by Analytical technique Raman Spectroscopy

A correct identification of gemstones is both of scientific significance (e.g. contributing to the systematics of minerals) as well has important commercial and ethical (e.g. conflict-free diamonds, fair trade) implications. The main hypothesis to be tested in this project is that subtle but meaningful deviations from nominal Raman spectra (as found in standard databases) will allow a unique assignment of specimens to specific gemstones, and to recognize imitations. Raman bands appearance, their intensity, positions and widths, as well as the nature of background (e.g. presence of fluorescence) will be used as proxies for assessment of the deviations in the course of spectral analyses. The origin of deviations include, for example, a minor variation in chemistry, presence of impurities and defects, degree of crystallinity, and presence of residual stresses in crystal structure indicating pressure-temperature conditions of synthesis. In some cases, such an approach, especially when combined with literature data, enables to reach beyond the goal of specimen identification in that it can pinpoint the geographic origin of the studied gemstone, or provide clues to the method of its synthesis.