Method for labeling products with a transparent photoluminescent label, and transparent photoluminescent label

A product comprising a photoluminescent pattern, wherein said pattern comprises:

• a photoluminescent portion which is transparent under normal light conditions and revealed by photoluminescence under UV illumination, said photoluminescent portion comprising a stack comprising successive pairs of layers, said pairs of layers each comprising a first layer of a first material with a thickness of less than or equal to 1 micron and a second layer of a second material with a thickness of less than or equal 10 nm, wherein the interface between the first layer and the second layer of the pairs of layers includes quantum nano-structures;
• a non-photoluminescent portion which is transparent under normal light conditions as well as under UV illumination, said non-photoluminescent portion comprising an additional transparent material or ions for raising the transparency.