A method of producing a data carrier with a marking is disclosed. The data carrier includes a laser-markable portion and a beam-modifying portion adjacent the laser-markable portion. The beam-modifying portion has a beam modifying property. The method includes irradiating a laser beam through the beam-modifying portion to allow the beam modifying property thereof to modify at least one beam property to produce a resultant laser beam. This resultant laser beam creates a marking with a visual impression corresponding to the resultant laser beam at the laser-markable portion. The method further includes modifying the beam modifying property of at least a part of the beam-modifying portion through which the laser beam is irradiated for creating the marking so that the exact same resultant beam is difficult to be obtained thereat. A data carrier thereby produced is also disclosed.