Coloured Diamond Deffect Idenditication by Raman Diffusion and Photoluminescence

Coloured Diamond Defect Identification by Raman Diffusion and Photoluminescence

Laser Raman microspectroscopy is a standard analytical technique in many gemmological laboratories. Such spectrometers can also be used to investigate luminescence emissions.

The set of analyzed diamonds consists of gemstones naturally coloured or colour enhanced by means of a specific treatment (heating, irradiation…). The aim of the following investigation is to determine if the photoluminescence (PL) generated by a UV excitation of these diamonds leads to significant differences depending on the technique used to colour the gemstones. Indeed, routine characterizations based on photoluminescence analysis already allow us to determine if the diamond is originally colourless or undergone a decolourisation treatment (High Pressure High Temperature –HPHT- treatment).

Photoluminescence analyses may also help to confirm that the colour of a diamond has been enhanced by an appropriate processing. The study initiated here tries to evidence the treatments (irradiation, annealing) that the diamond could have undergone to look more intensely coloured.

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Coloured Diamond Defect Identification by Raman Diffusion and Photoluminescence
DescriptionThe colour enhancement treatment on native brown and yellow diamonds can be highlighted by Photo Luminescence analyses performed with the Raman spectrometer LabRAM HR. The PL signature of green and violet diamonds has also been recorded. The defect centres responsible of the colour of the diamonds have all been detected and assigned. This proves the Raman spectrometer to be a very good tool to investigate the fine defects in the Diamond structure by Photoluminescence analysis.
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