A densely sintered high-purity alumina has been successfully utilized as a coping for all-ceramic crown. In order to apply the alumina coping to the porcelain laminate veneer restoration for the discolored teeth, the present study evaluated its masking ability when it was thinner than the proposed thickness for the crown. Colorimetric examination was performed on white and black backgrounds for the 0.7mm thick porcelain laminate veneer with 0.40 or 0.25mm thick alumina coping and 0.7mm thick porcelain without coping. With the presence of the coping, the porcelain appeared significantly lighter. Judging from the calculated color differences ΔE and the literature, it was suggested that the masking ability of the alumina coping would be sufficient with a 0.25mm thickness for the porcelain laminate veneer for heavily discolored teeth.