Disclosed is a glass containing one or more rare earth elements and one or more halides, wherein the glass comprises a region converted into a crystalline glass containing a precipitated halide crystallization containing rare earth elements. A molded object comprising a dispersed glass particle is also disclosed, wherein the glass comprises one or more rare earth elements and one or more halides, wherein the object has an area in which the particles are converted into crystalline glass granules. The crystalline region is invisible under normal light, but can be detected using a frequency-conversion luminescence generated by laser radiation with a specific wavelength. The method of preparing the local crystalline glass and the molded object is also disclosed, and the method for the efficient detection of the crystalline region in the glass or molded object is presented.
