The International Gemological Institute (IGI) has established a set of procedures for successfully separating fancy-colored natural diamonds from synthetics, which can often be difficult to screen due to treatments.
The lab came up with a method for screening each color category using advanced techniques such as Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy, together with magnification, it said last week. Traditional screening devices generally use photoluminescence to capture a diamond’s fluorescence and phosphorescence under ultraviolet light. However, that method often doesn’t work with fancy-colored lab-grown because the stones may be treated with irradiation, heat and pressure, which alters their fluorescence and phosphorescence, IGI explained.
