The main goal of this work was to study the formation of theluster effect in a glaze manufactured from a ceria-containingfrit. The glazes obtained under industrial firing were studied usingX-ray photoelectron spectroscopy, X-ray diffraction at roomtemperature and high temperature, and scanning electron microscopywith energy-dispersion spectroscopy. The mechanismof the luster effect on the surface was explained. The resultsindicated that the glaze presents iridescent colors on the surface,mainly associated with the formation of a very thin layer ofCeO2 crystals.Moreover, the CeO2 crystals show a preferentialorientation and different dimensions. The CeO2 crystallizationon the glaze was also studied using a hot-stage X-ray technique.