Structural colours are unlike colours produced by chemical dyes and pigments in that they originate from resonant interactions between visible light and engineered nanostructures. These colours do not fade over time – the way ink does. A team of researchers from the US and Belgium has now developed a simple, one-pot reverse emulsion process to assemble silica-coated melanin nanoparticles to produce bright structural colours that mimic the structure of duck feathers. The “photonic supraballs”, as they are called, could replace toxic metal oxides and other pigments used to create colours and might be directly added to paints, plastics and coatings. They could even be used as UV-resistant inks and cosmetics…..