Digital GIA LED Fluorescence Device. GIA uses a custom-made fluorescence meter with LWUV LEDs to measure the fluorescence intensity documented on its diamond grading reports. Designed to improve fluorescence measurement consistency, this instrument uses an LED excitation source with a single emission peak at 367 nm and an FWHM of 14 nm (figure 4E).
UV LED Loupe. A generic commercial UV loupe sometimes used in the trade (figure 2C) was also examined. The LED excitation source from this loupe gave a single peak at 403 nm with an FWHM of 17 nm (figure 4F).
Commercial LED Light Source. For comparison with the other LED sources, we also tested a commercially available “365 nm” LED light source manufactured by Ocean Optics (figure 2D). This excitation source showed a single peak at 364 nm with an FWHM of 10 nm (figure 4G).