Abstract: A method of identifying a gemstone, particularly a diamond by: exciting the gemstone to cause it to emit luminescence radiation according to a luminescence spectrum unique to the respective gemstone, in which the luminescence intensity uniquely varies as a function of wavelength; measuring the level of the luminescence radiation at a plurality of preselected wavelengths of its luminescence spectrum; and utilizing the levels of the luminescence radiation at the preselected wavelenths to identify the respective gemstone and to distinguish it from other gemstones.