When it comes to shiny things, people always tend to think of things like gemstones, metals or pearls. Sometimes even certain stones. Can't blame them too much, it is after all what we see most often. Heck, I even remember the episode of mythbusters where they polished balls of poo in honor of the turn of phrase stating such a thing. The thing here however, is that most of these things require the tools of humans to bring out that natural shine.
Nature provides some pretty epic examples of natural shine. The scales of a fish, the exoskeleton of many insects, even the metallic refraction on the feathers of many birds. The true winner though is actually a berry. The Pollia condensata berry from Africa if the single shiniest natural object on Earth, reflecting upwards of 30 percent of all light that touches it. Kew Gardens, the University of Cambridge and the Smithsonian Natural History Museum quickly moved in and tried to figure out exactly what it was the berry was using to produce its beautiful shine.
They hoped to find the pigment behind it all. After all, color as we see it is in reality an illusion, created when light enters, bounces around and exits a pigment, allowing us to see it. However in this case, there was no pigment involved. Nanoscale structure was the answer.
This structure causes reflected light to basically crash into itself, which in turn causes layers of cells to scatter and reflect incoming light. At that point, light bouncing around inside different layers become more intense. Once it finally escapes, it appears blue, with bits of red or purple for the light particles that managed to escape between layers. Not too different than butterfly wings and bird feathers. Apparently the berries taste great too.