Isn't this pretty? It's a little fruity berry type thing called Pollia condensata, from Africa, and it's the shiniest thing on the planet. We're talking "shiny" like Firefly shiny: something brilliant and awesome and sparkly that lasts forever, because there's no actual pigment going on in there. The color is structural, like a butterfly wing, and will never ever fade.
Officially, the P. condensata fruit is the most intense natural color there is, reflecting a massive 30% of the light that falls on it. Researchers from Kew Gardens, the University of Cambridge and the Smithsonian Natural History Museum wanted a piece of the action, so they all tried to figure out what kind of pigment P. condensata was using, but after attempting to extract said pigment they realized that there wasn't any. At all.
We generally think of colors in terms of pigments: some sort of chemical that reflects a particular wavelength of light. If you've got a red pigment, for example, it absorbs all wavelengths of light except for red, which it reflects, which is why it looks red. Simple.
What's less simple is what this fruit has come up with to produce its color: it's using nanoscale structural cleverness that causes reflected light to constructively and destructively interfere with itself. Twisting layers of cells scatter and reflect incoming light, and as the light bounces around inside layers, it gets intensified, and by the time it makes it out it's a vivid blue color. Slight differences in the spacing of the layers inside the fruit also create glittering reds, greens and purples.
Butterflies do this same sort of thing, as do birds, but this is the first time it's been seen in a plant, and the plant has knocked it out of the park in terms of intensity. The point of this feature, as far as the plant is concerned, is that the fruit it creates is blindingly eye-catching, but it's not good for anything else — it has no nutritional value at all. However, P. condensata grows right next to a different bush, also with blue berries, that are tasty. So what's probably going on is that P. condensata's iridescent fruits are designed to trick animals into eating them by mistake, allowing the plant to spread its seeds without actually having to invest in bribery. Genius.