
It was previously suggested that the reptiles' famous ability came from gathering or dispersing coloured pigments inside different cells.
But the new results put it down to a "selective mirror" made of crystals.
They also reveal a second layer of the cells that reflect near-infrared light and might help the animals keep cool.
Reptiles make colours in two ways: they have cells full of pigment for warm or dark colours, but brighter blues and whites come from light bouncing off physical elements like these crystals: so-called "structural colours".
These colours can also be mixed. A vibrant green might arise from a structural blue overlaid by yellow pigment.
http://www.bbc.co.uk/news/science-environment-31819588