This work presents an analysis of the crystallization process and the influence of laser surface modification on the crystalline phases and optical responses of Al2O3/glass–ceramic coatings deposited on a brass substrate. We used a CO2 laser at different irradiation powers to change the structure of the superficial layer. The photoluminescence response enhanced the resolution of its line shape as the irradiation power increased. X-ray diffraction patterns exhibit the presence of different crystalline phases for the samples irradiated.