Since then, several alternative light sources havebeen introduced that are considerably advanced intheir technology, light output, and size. UV-rangeLEDs have improved significantly in the last fewyears, and have a high energy output that enablesthe use of a high-resolution spectrometer and shorterintegration times (figure 8). They also surpass stan-dard gemological lamps in that they provide only avery narrow band of UV radiation. These UV sourceshave resulted in significant improvements in thequality of fluorescence and phosphorescence spectra.