Visual Luminescence and Luminescence Imaging

Abstract

Visual luminescence excited by UV light and luminescence imaging are discussed as simple and effective techniques for preliminary characterization of diamonds and as methods of recognition of HPHT-treated diamonds. Since all natural diamonds fluoresce under UV excitation, the visual luminescence technique is a common method applicable to diamonds of all types. The change of luminescence color after HPHT treatment and the formation of characteristics luminescence patterns in HPHT-treated diamonds are discussed. It is shown that the enhancement of luminescence on macroscopic defects and the concentration of luminescence intensity on the facet junctions of cut diamonds (“fluorescence cage” effect) are very characteristic features of HPHT treatment, which are particularly prominent in type I HPHT-treated and irradiated diamonds.