The method determines laser stability of an optical material, which is suitable for making an optical element through which high-energy light passes. The method includes pre-irradiation to produce radiation damage and measurement of the resulting induced non-intrinsic fluorescence. The method is distinguished by excitation of induced fluorescence immediately after pre-irradiation and after at least ten minutes after pre-irradiation with light of a wavelength between 350 and 810 nm, and measurement and quantitative evaluation of fluorescence intensities at wavelengths between 550 nm and 810 nm. Especially laser-stable optical materials, particularly CaF.sub.2 crystals, have a normalized difference (Z) of the fluorescence intensities measured at a first time immediately after pre-irradiation and at a second time at least ten minutes after the pre-irradiation, as calculated by the following equation (1): Z=(I.sub.2,.lamda.1,.lamda.2-I.sub.1,.lamda.1,.lamda.2)I.sub.2,.lamda.1,.- lamda.2 (1), which is less than 0.3.