The invention is directed to a method by exposing at least a portion of a luminescent coating disposed on a surface of an article to ultraviolet light at one or more preselected wavelengths causing said luminescent coating to exhibit a luminescence spectrum, the luminescence spectrum exhibiting a plurality of intensity peaks that have been predetermined to create a standard; determining the intensity of at least two peaks in the luminescence spectrum of the coating; determining a peak intensity ratio of the at least two peaks; comparing the peak intensity ratio determined with the standard; and, classifying the article according to whether or not the peak intensity ratio does or does not match the standard; wherein the luminescent coating is a particulate luminescent composition comprising a rare earth doped fluoride represented by the chemical formula RE.sub.x(Ca.sub.aSr.sub.bBa.sub.c).sub.1-xF.sub.2+x-2yO.sub.y wherein RE represents a three-valent rare-earth element, 0.005.ltoreq.x.ltoreq.0.20, and 0.ltoreq.y.ltoreq.0.2, a+b+c=1, with the proviso at least two of a, b, and c are not equal to zero; the particulate luminescent composition exhibiting a luminescence spectrum having a plurality of intensity peaks at characteristic wavelengths.