A transparent aluminum oxynitride product is produced by a first heat treating step wherein a combination of Al₂O₃ and AlN at a temperature within the solid-liquid phase and a second step of sintering the heat treated combination at a temperature at least 50 C. less than the heat treating temperature. The method introduces a small fraction of liquid that aids in pore elimination and densification. In a single step, the material is shifted from the liquid/solid region into a solid AlON solution region, wherein the liquid is fully reacted with the solid AlON phase, with further sintering occurring. The procedure is sufficient to eliminate voids and other imperfections which often result in a reduction in optical clarity.