The diamond weevil, which makes its home in the Brazilian tropics, has a body studded with tiny, brilliant reflectors. Each one is like a diamond, reflecting different-colored light in shiny arrays. New research has probed the microstructure of these brilliant facets and discovered that the way they work is familiar—but the way they are made is not.

These insect “diamonds” are not made of carbon like the diamonds in a jewelry store, but instead contain the same sugar-based molecules called chitin that comprise the rest of their outer cuticle. But the 3-dimensional arrangement of the sugar molecules is precise and orderly. In their report published in the Journal of the Royal Society Interface, the researchers called them “biological photonic crystals that act as wavelength-specific reflectors.”1

The investigators shone a tiny, focused beam of light on each of the weevil’s crystals to peer into its molecular arrangement. It resembled the pentagon and hexagon panels of a soccer ball, but the insects’ gem surfaces form hexagon and square “panels” like those of diamond facets.

The study authors compared the crystalline shape to other theoretically possible shapes and deduced that the weevil crystals have the best possible shape to reflect the maximum amount of light. They wrote, “Extremely large biophotonic nanostructures of E. imperialis [diamond weevil] are structurally optimized for high reflectance.”1

Lead author Bodo Wilts told Wired Science, “We’ve got some catching up to do.….The nature-produced tiny structures are far beyond any human designs.”2

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