Traceability of Diamonds Using UV-VIS-NIR Spectroscopy

Diamond traceability has been a major challenge for the gemological industry in recent decades. In this context, this paper presents new studies using UV-VIS-NIR spectroscopy to identify the traceability and geographical origin of diamonds. The aim of the work is to identify characteristic centers of fancy-color diamonds collected from Cullinan Mine, Democratic Republic of Congo (DRC), and the geographical regions with unknown origin. Depending on the origin of the diamonds, the UV-VIS-NIR spectra can be differentiated as follows: (i) the diamonds collected from Cullinan Mine show absorption bands assigned to N10, NV0, NV−, N3V0, N4V2, and N4V centers, which are accompanied by a vibronic structure localized between 415 and 394 nm (2.987–3.147 eV) and (ii) the diamonds from DRC show absorption bands attributed to N10, NV−, N3V0, N1+, and NVH centers. Using Raman spectroscopy, nitrogen concentration values of diamonds collected from the Cullinan mines and DRC between 41 and 185 ppm and 204–336 ppm, respectively, were reported. We prove that the simultaneous applicability of UV-VIS-NIR spectroscopy and Raman scattering as comparative tools for assessing diamond provenance can be a valuable strategy for an initial attribution of diamonds with unknown geographical origin, knowing the optical features of diamonds collected from Cullinan Mine and DRC.