Origin Determination

GemTOF can measure unique chemical fingerprints consisting of major, minor, trace and even ultra-trace elemental compositions in gemstones due to their various formation conditions and chemical environment. Although it requires a minute ablation volume at the surface (normally on the girdle) of a gem, GemTOF provides valuable chemical data in addition to traditional gemmological analyses. This opens up important opportunities for origin determination of gemstones such as emerald, ruby, sapphire, spinel, alexandrite, garnets and other coloured gems. The acquired chemical information can be displayed in different types of plots in order to categorize gemstones in groups (often gemstone origins).

To illustrate the use of GemTOF, full mass spectra of four sapphires of documented provenance is shown below. The quantitative results of trace elements Magnesium (Mg), Iron (Fe) and Gallium (Ga) are plotted in a three-dimensional scatter plot together with data from a previous study (Halicki, 2013) using LA-ICP-Q-MS on sapphires documented from Kashmir, Sri Lanka and Myanmar of SSEF reference collection with various color saturation. The scatter plot reveals that these reference sapphires from three origins (circles) plot in noticeably separated areas. The four sapphires analyzed by GemTOF (triangles) fit well into the expected plotting areas for the Kashmir, Sri Lanka and Myanmar origins.