The effects of additions of zircon (5–17 wt%) to conventional single firing ceramic glazes is examined. The structural and morphological characteristics of the glazes were determined by Scanning Electron Microscopy, X-ray diffraction, infra-red spectroscopy, as well as 27Al and 29Si magic angle spinning (MAS) NMR. The presence of zircon microcrystals was revealed by X-ray diffraction (XRD) combined with scanning electron microscopy (SEM) and EDAX microanalysis. The chemical durability of the glasses is revealed to be acceptable for certain practical applications. The color characteristics of the glazes obtained were estimated in the HunterLab system (L*C*h*, emission spectra). The outcomes of the study established correlations between composition, structure and some of the physical properties.