In restoration dentistry clinicians need to control the effect of the ceramic thickness and cement shade to achieve successful colorimetric results when all-ceramic veneers are bonded. The purpose of this study was to evaluate the in vitro effects of cement color and the thickness of the final shade on porcelain discs. The study sample comprised 120 e.max Press HT A-2 ceramic discs of two thicknesses (60 of 1 mm thick and 60 of 0.5 mm thick). Three different lightnesses of Variolink Veneer cement were used (-3, 0, and +3) for the cementation process. An Easyshade spectrophotometer was used to measure color coordinates (L*, C*, h, a*, and b*) on the discs both before and after cementation. To a large extent, color changes (Eab) after the cementation process were found to depend on cement thickness, ceramic thickness, and cement lightness. This model predicted 52% of the observed variability. The most marked change in color appeared on discs 0.5 mm thick and a cement lightness of -3 (Eab=12.0 units). By contrast, color was more stable (minor changes) on discs with a cement lightness of +3 (Eab=2.3 units). All color coordinates were significantly modified after bonding, both on thin and thick discs and in all three cement color groups (-3, 0, and +3). However the difference in color (Eab) is significantly greater in discs 0.5 mm thick as compared with ceramic discs 1 mm thick. The most prominent change after bonding was found in the h (hue) coordinate. (c) 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 642-648, 2016