A method of making an authenticatable label (150) is disclosed. The method includes applying a printing (190) to a first side of a substrate (180), applying a taggant (300) to a second side of the substrate, wherein the taggant emits luminescence in response to illumination by an excitation signal. The method further comprises applying an adhesive (200) to the second side of the substrate, wherein following application of the adhesive to the second side of the substrate at least a portion of the taggant migrates into the adhesive.