“You can put it on a wine bottle, a gold watch, a painting—whatever. The label needn’t be larger than a comma. And, it is impossible to copy because the probability that two items share the same fingerprint is nil.
The fingerprint, or “tag,” consists of a bit of transparent ink
containing various microparticles that researchers can spray on a bar
code on paper, for example. The researchers based their system on PUF
technology (physical unclonable function). Like a scattered handful of
sand, the particles form a random, completely unique pattern of tiny
white dots when applied. As there is no chance of creating identical
patterns using this method, as it is impossible to copy."