Specific spectroscopic features of yellow cuboid diamonds from placers in the north-eastern siberian platform

Abstract

A series of yellow cuboid diamonds from alluvial placers in the north-eastern Siberian platform have been examined with Fourier-transform infrared (FTIR) absorption spectroscopy, photoluminescence (PL) and electron paramagnetic resonance (EPR). All crystals having characteristic FTIR spectra with predominantly C and A centres belong to mixed type IaA/Ib with small total nitrogen content (up to 330 ppm). PL is characterized by many bands with two bands related to the NV0 and NV– centres common to all the samples. The FTIR spectra are also characterized by deformation-induced ‘amber’ centers. Some of the yellow diamonds studied show new bands at 4272, 4548, and 5960 cm–1 instead of the bands at 4060 and 4170 cm–1 common for ‘amber’ centres. An EPR study has revealed the presence of OK1 centres associated with titanium impurity. The plastic deformation of the studied diamonds is expressed as a ‘tatami’ strain pattern in the features of their internal structure.