Disclosed is a dry gypsum composition containing hemihydrate gypsum, at least one pigment and a crystal habit modifier. The crystal habit modifier is at least one compound selected from the group consisting of sulfate salts, carboxylate salts, carbonate salts and inorganic chlorides, and a content of the at least one compound is in a range of 0.1 to 5 parts by mass per 100 parts by mass of the hemihydrate gypsum, whereby upon hydration of the hemihydrate gypsum into dihydrate gypsum, the dihydrate gypsum is controlled to become plate crystals having an aspect ratio of 1 to 9. A gypsum-based coating formulation making use of the dry gypsum composition is also disclosed.