Granulated zinc metal films on fused quartz and sapphire supports were obtained via pulsed laser deposition and then oxidized in air at different temperatures. We found that optical absorbance spectra of oxide films do not depend on the oxidation temperatures from 400 to 750 °C. The spectra are characterized by the fundamental absorption edge and the exciton maximum at 370 nm. At the oxidation temperature of 770 °C, the optical absorbance spectrum changes dramatically. The fundamental absorption edge was shown to shift to shorter wavelength, thereby heralding the growth of the band gap. To elucidate the origin of the observed phenomena, the films stoichiometry was studied via X-ray photoelectron spectroscopy (XPS). Band edge luminescence was observed independent of the oxidation temperature. On the other hand, visible luminescence at 500 nm occurs only at the oxidation temperatures higher than 600 °C and grows afterward. According to the results of XPS, the reason for the appearance of that luminescence peak is the appearance of oxygen vacancies at oxidation temperatures above 600 °C.