Geosciences and gemology

In the field of gemology, both Raman and photoluminescence information is widely used to identify whether diamonds have been artificially treated at high temperature and pressure (known as HPHT treated or GE-POL diamonds) to change their colour and hence value. In addition to gemstone classification, Raman is utilised to identify inclusions, fillers, waxes and other treatments that have an impact on gem valuation. Geologists and mineralogists use Renishaw's structural and chemical analyser (SEM-SCA) to benefit from the imaging and analytical capabilities of scanning electron microscopes (SEMs) combined with the chemical and structural characterisation provided by Raman spectroscopy.

In this example, elemental dispersive spectroscopy (EDS) analysis was used to discriminate between different species from a sectioned piece of Sandstone from Loch Torridon, Scotland. Using these classifications, Raman analysis was able to determine the chemical composition and polymorphic forms of the sample, allowing the rapid, simultaneous and unambiguous identification of the constituent phases on the macro and micro scales. Other downloads describe the analysis of a meteorite section, cement clinker and mineral sands using Renishaw's SEM-SCA.

Selected publications

Liddicoatite tourmaline from Aanjanabononia, Madagascar (2002), D M Dirlam et al, Gems & Gemology, 38, 28-53

Identification of GE POL diamonds: a second step (2000), J L Chalain et al, Journal of Gemmology, 27, 2, 73-78

Detection of GE POL diamonds: a first stage (1999), J P Chalain et al, Revue de Gemmologie A. F. G., 138/139, 30-33

On the identification of Amber and its imitations using Raman spectroscopy – Preliminary results (1998), T S Tay et al, Australian Gemmlogist, 20, 114-123