  The nanostructures of natural species offer beautiful visual appearances with
saturated and iridescent colors and the question arises whether we can
reproduce or even create new appearances with man-made metasurfaces. However,
harnessing the specular and diffuse light scattered by disordered metasurfaces
to create attractive and prescribed visual effects is currently inaccessible.
Here, we present an interpretive, intuitive and accurate modal-based tool that
unveils the main physical mechanisms and features defining the appearance of
colloidal disordered monolayers of resonant meta-atoms deposited on a
reflective substrate. The model shows that the combination of plasmonic and
Fabry-Perot resonances offers uncommon iridescent visual appearances, differing
from those classically observed with natural nanostructures or thin-film
interferences. We highlight an unusual visual effect exhibiting only two
distinct colors and theoretically investigate its origin. The approach can be
useful in the design of visual appearance with easy-to-make and universal
building blocks having a large resilience to fabrication imperfections, and
potential for innovative coatings and fine-art applications.
