Crime scene investigators are about to get a helping hand from our ancient ancestors. The earliest known synthetic pigment, Egyptian blue, is found in some of the paint on ancient statues, coffins, tomb walls, and amulets. Most other pigments long ago faded. Modern scientists, intrigued by its longevity, worked out Egyptian blue’s chemical composition decades ago. Recently it was discovered that it emits near-infrared radiation when exposed to certain kinds of light. Basically: it has rare, invisible luminescence.
And why does that help crime-stoppers? Egyptian blue can be dusted onto complicated surfaces where fingerprints are normally hard to retrieve. The surface is then photographed with a modified camera and a filter sensitive to Egyptian blue’s near-infrared rays. If fingerprints are there, they glow clearly in the resulting image. Science is amazing.