|Researchers have found that 'Egyptian blue' is 10 times more fluorescent than previously thought. Fluorescence is the emission of light from an object as a result of bombardment by other kinds of light or electromagnetic radiation. Previous research has shown that when Egyptian blue absorbs visible light, it subsequently emits light in the near-infrared range. Considered to be the first synthetic pigment, Egyptian blue—which is derived from calcium copper silicate—was routinely used on ancient depictions of gods and royalty in ancient Egypt. It was known to the Romans as "caeruleum," but after the Roman era the pigment fell from use.|
As well as its potential to cool buildings, the fluorescence of Egyptian blue could also be harnessed to generate energy. If solar cells are applied to the edges of windows tinted with the blue pigment, they could convert the high quantities of reflected near-infrared energy to produce electricity.