Raman and Photoluminescence Mapping of Gem Materials

Raman and photoluminescence (PL) mapping is a non-destructive method which allows gemologists and scientists to evaluate the spatial distributions of defects within a gem; it can also provide a method to quickly distinguish different species within a composite gem. This article provides a summary of this relatively new technology and its instrumentation. Additionally, we provide a compilation of new data for various applications on several gemstones. Spatial differences within diamonds can be explored using PL mapping, such as radiation stains observed on the rough surface of natural green diamonds. Raman mapping has proven useful in distinguishing between omphacite and jadeite within a composite of these two minerals, identifying various tourmaline species within a heterogeneous mixture, and determining the calcium carbonate polymorphs in pearls. Additionally, it has potential to be useful for country-of-origin determination in blue sapphires and micro-inclusion analysis. As new avenues of research are explored, more applications for gem materials will inevitably be discovered.

Automated summary

Raman and photoluminescence (PL) mapping is a non-destructive method that helps evaluate spatial distributions of defects within gems and differentiate different species in composite gems. It can be used to explore spatial differences in diamonds, distinguish minerals within composites, identify structures in pearls, and potentially aid in origin determination and micro-inclusion analysis in gemstones. As research progresses, more applications for gem materials are expected to be uncovered.