Ultraviolet-Visible (UV-Vis) spectroscopy measures the attenuation of light across the ultraviolet (200–400 nm) and visible (400–700 nm) spectral regions. It is one of the most widely established quantitative analytical techniques in science and industry.
UV-Vis spectra result from electronic transitions within molecules, notably π → π* and n → π* transitions, as well as metal-ligand charge transfers and crystal field d-d electron transitions that give gemstones their vibrant natural hues.
Governed by the Beer-Lambert law, UV-Vis enables exact quantitative concentration determination. In gemology, it serves as a critical screening standard for identifying heat treatments, irradiation indicators, and dye saturation in corundum, beryl, and diamonds.