Such structural colouration causes the iridescence of the peacock's hues. His wings are black with a less conspicuous bluish iridescence. It is slender-bodied and silvery with pinkish iridescence on its sides. Kadaknath birds are grey-black all over and have gold plumage with greenish iridescence. Interference can also be seen in everyday phenomena such as iridescence and structural coloration. However, most of these molluskan pearls have no luster or iridescence. All these species have generally black plumage with varying amounts of green and blue iridescence. Elytra and pronotum have a beautiful metallic emerald iridescence. Green colors and metallic iridescence are generally absent. The female is brownish-grey with slight hints of the male's iridescence. Their wings were valued for their beautiful and hardy metallic emerald iridescence. He also found that bleaching the pigments from the feathers did not remove the iridescence. Juveniles are duller and grayer than adults and lack iridescence. Some specimens have a red iridescence within the gray-black crystals; these are called "ruby sphalerite". Animals that show iridescence include mother of pearl seashells, fish, and peacocks.