In planarization processes of sapphire, lapping process takes a long time because sapphire is a hard material. In contrast, superfinishing, which involves fixed abrasive machining, can substitute for lapping, and it would be possible to shorten the amount of processing time. In this work, vitrified-bonded diamond superabrasive stones with different grain diameters are developed. Then, multistage superfinishing is investigated by combining these stones. Results indicate that the multistage process is capable of producing a 2 nmRa surface, equivalent of a lapped surface in less than 10 min. To improve the process of multistage superfinishing, a removal amount estimation method is developed based on the real contact pressure calculation. The working area ratio of the stone was calculated by considering elastic deformation during superfinishing. The contact ratio of sapphire is calculated considering the roughness of the pre-finished surface and grain depth of cut. Accordingly, the real contact pressure is calculated to estimate the removal amount during superfinishing and finished surface roughness was expected.