Deep-colored fibrous articles, such as fabrics colored in a deep black shade, having on it surfaces a film coating of a resin mixture comprising at least two resins that are mutually miscible but incompatible and in phase-separated conditions. Color-deepening effect is augmented by forming pits and/or recesses and projections on the surfaces of the film coating by using resins different in solvent-solubility and eluting the resin having a larger solubility with a solvent. The above effect is further augmented by using resins different in plasma etching resistance and subjecting the formed film coating to a low-temperature plasma etching treatment. The plasma etching is effectively conducted by placing the fibrous article within a plasma sheath, preferably contacting with an antenna electrode. The deep color can be made abrasion resistant by further depositing an abrasion resistant resinous film on the pit-formed resinous film coating without filling up the pits.