The device for satinizing and embossing flat materials comprises an embossing roll and at least one mating roll, said rolls being connected to a driving system and adapted to be driven individually or in common and to be resiliently pressed against one another while the individual teeth are flattened, and the embossing teeth being designed such as to produce in the corresponding locations of said flat material during its passage embossed marks whose appearance varies according to the viewing angle of the observer and/or the kind and/or the position of the lighting source, the embossing teeth which produce said variable marks having a different geometrical shape and/or surface than the satinizing teeth intended for satinizing. To this end, the surfaces of said embossing teeth and/or portions of the tooth space bottom are provided with microstructures. These microstructures allow producing largely forgery-proof marks which may furthermore provide a very decorative effect.