Method for embossing a first grating in a planar material, by means of an embossing body and a counter embossing body, having each a hard surface, the first grating to be embossed comprising alternating substantially parallel and straight ridges and recesses, whereby the top surfaces of the ridges are intended to weaken a direct angular reflection of light by diffuse omnidirectional reflection, thereby producing a visible contrast between the ridges and the recesses, the method comprising on the embossing body providing a first plurality of obtuse pyramids with respective bases which are on the hard surface of the embossing body, and the obtuse summits of which face away from the hard surface of the embossing body, the first plurality of obtuse pyramids being intended to emboss the recesses of the first grating by exerting pressure on a first side of the planar material, the first plurality of obtuse pyramids forming first intermitted lines (row1, row2) corresponding to the intended recesses, and the pyramids in each subset corresponding to one of the first intermitted lines, being separated from each other between their bases by a determined distance that creates a gap in the line in such a manner that each gap from a line of pyramids may be connected to a corresponding gap from an adjacent line of pyramids by an imaginary line perpendicular (row1', row2') to both of the adjacent lines; roughening portions of the hard surface of the embossing body, the portions being located between adjacent lines of pyramids and intersecting at least one of the imaginary lines that connect one gap from one line to the corresponding gap from the adjacent line; on the counter embossing body providing a second plurality of obtuse pyramids with respective bases which are on the hard surface of the counter embossing body, and the obtuse summits of which face away from the hard surface of the counter embossing body, the second plurality of obtuse pyramids being intended to emboss the ridges of the first grating by exerting pressure on a second side of the planar material opposite to the first side, the second plurality of obtuse pyramids forming second intermitted lines (row3, row4) corresponding to the intended ridges, and the pyramids in each subset corresponding to one of the second intermitted lines, being separated from each other between their bases by the determined distance, and the pyramids being positioned on their respective second intermitted lines in such a manner that during embossing their obtuse summits press the planar material against a roughened portion of the hard surface of the embossing body, thereby satinizing the top surfaces of the ridges on the first side; the method being characterized in that the respective bases of the first plurality of obtuse pyramids and the respective bases of second plurality of obtuse pyramids are rhomboid-shaped bases. on the embossing body providing a first plurality of obtuse pyramids with respective bases which are on the hard surface of the embossing body, and the obtuse summits of which face away from the hard surface of the embossing body, the first plurality of obtuse pyramids being intended to emboss the recesses of the first grating by exerting pressure on a first side of the planar material, the first plurality of obtuse pyramids forming first intermitted lines (row1, row2) corresponding to the intended recesses, and the pyramids in each subset corresponding to one of the first intermitted lines, being separated from each other between their bases by a determined distance that creates a gap in the line in such a manner that each gap from a line of pyramids may be connected to a corresponding gap from an adjacent line of pyramids by an imaginary line perpendicular (row1', row2') to both of the adjacent lines; roughening portions of the hard surface of the embossing body, the portions being located between adjacent lines of pyramids and intersecting at least one of the imaginary lines that connect one gap from one line to the corresponding gap from the adjacent line; on the counter embossing body providing a second plurality of obtuse pyramids with respective bases which are on the hard surface of the counter embossing body, and the obtuse summits of which face away from the hard surface of the counter embossing body, the second plurality of obtuse pyramids being intended to emboss the ridges of the first grating by exerting pressure on a second side of the planar material opposite to the first side, the second plurality of obtuse pyramids forming second intermitted lines (row3, row4) corresponding to the intended ridges, and the pyramids in each subset corresponding to one of the second intermitted lines, being separated from each other between their bases by the determined distance, and the pyramids being positioned on their respective second intermitted lines in such a manner that during embossing their obtuse summits press the planar material against a roughened portion of the hard surface of the embossing body, thereby satinizing the top surfaces of the ridges on the first side; the method being characterized in that the respective bases of the first plurality of obtuse pyramids and the respective bases of second plurality of obtuse pyramids are rhomboid-shaped bases.