The Present and Future Potential of Raman Spectroscopy in the Characterization of Gems and Minerals.

A number of important breakthroughs have occurred in recent years that allow Raman spectroscopy to be considered as a routine but powerful analytical tool for identifying and characterizing natural crystalline compounds. The long-standing limitation in sensitivity and the detection limit capabilities of conventional Raman have now dropped to the levels of parts per million and lower. These developments have resulted from a combination of technological advances in optical components, sources, and detector technology. Advanced technologies developed for fiber-optic telecommunication are now being applied to implement an entirely new generation of miniature spectrometers. Optical systems for entire spectrometers can be built in volumes of cubic millimeters. New approaches for optical component fabrication, mounting, and alignment have been developed that yield highly robust systems capable of providing exceedingly high levels of performance. Performance considerations and design "trade-offs" include resolution, excitation, wavelength, sensitivity, size, and weight. A new generation of handheld Raman spectroscopic instrumentation is currently being introduced that will find application in diverse fields such as process control, product quality control, medical diagnostics, and environmental analysis, as well as in the analysis of gems and minerals. The use of Raman spectra to assist in the nondestructive identification of gems, however, requires a credible database as well as appropriate search algorithms. Such a database is currently being developed by the RRUFF project as a public domain asset (http://rruff.info), sponsored by Mike Scott. [ABSTRACT FROM AUTHOR]