Gray-to-Blue-to-Violet Hydrogen-Rich Diamonds from The Argyle Mine, Australia

thousands of small stones provided an updated view of these spectral characteristics for H-rich diamonds in general, including the HGBV color group (Fritsch et al., 2007a). All these studies showed that the IR spectra-of all the color groups of H-rich diamonds-are dominated by H-related peaks, and suggested that their UV-Vis spectra may be influenced by the relatively high H content. Photoluminescence (PL) optical characterization (Iakoubovskii and Adriaenssens, 2002) and electron paramagnetic resonance (EPR) measurements