This study compared the translucency of IPS e.max all-ceramic system of A and D color series veneered and glazed at clinically appropriate thicknesses. Core specimens (n = 5) of IPS e.max were produced and veneered with IPS e.max veneering porcelain to final dimensions (13 mm in diameter, 0.6 mm in thickness for core specimens with a thickness of 0.3 and 1.0 mm for core specimens with a thickness of 0.5 mm). Luminous reflectance was measured three times each specimen with a calibrated spectrophotometer after veneering and again after glazing cycle. Contrast ratios (CR=Yb/Yw) were measured from the luminous reflectance (Y)of the tested specimens with a black (Yb) and a white background (Yw). There was no significant difference in contrast ratios of specimens within the same color series before and after glazing (P > 0.05). Significant difference was found in the contrast ratios of specimens of the same color but different thickness before and after glazing (P < 0.05). The specimens with a thickness of 1.0mm presents significantly higher contrast ratios than specimens of the same color with a thickness of 0.6mm before and after glazing. The contrast ratios of glazed specimens were significantly lower than nonglazed ones. The Contrast ratio increases as the thickness of the core veneer materials increase, while luminosity and chroma are not related to relative translucency. The glazing cycle results in decreased opacity for core veneer materials.