Comparison between Greenish-Blue and Orange Phosphorescence in HPHT Synthetic Diamond

Besides the greenish-blue one, the orange phosphorescence (-590 nm, 2.1 eV), reported by Watanabe et al., in 1997, is another diagnostic feature for separating high-pressure-high-temperature (HPHT) synthetic diamonds from others. Interestingly, the greenish-blue phosphorescence probably has some connection with the orange one. For instance, the greenish-blue one decays much faster in diamonds which contain both phosphorescence features. However, the basic description of the orange phosphorescence is still limited. Using photoluminescence (PL), thermoluminescence (TL) and other technologies, we characterized the optical features of the orange phosphorescence. It is highly likely due to other defects, rather than the nitrogen-boron pair (Zhao et al., 2023; Zhang et al., 2023), for its distinct excitation, polarization and thermoluminescence features.