BERLIN: Scientists in Switzerland have found a way to make brown chocolate colourful, without adding further ingredients.

The Swiss Federal Institute of Technology said Thursday that researchers discovered a method to imprint a special structure on the surface of chocolate that makes it shimmer and shine like a rainbow.

The university said the process mimics the effect of chameleon skin, which can change to display specific colours.

It said the rainbow chocolate is ready for industrial production and the scientists are already in talks with big chocolate makers.