Within the plumage of a peacock lies a complex architecture that's continuously changing color. Or so it seems. Though the colors of a peacock are revered, it is just as stunning--if not more so--without them. Often referred to as an albino peacock, it is nothing of the sort. It's technically a white peacock which is a genetic variant of the Indian Blue Peafowl.
The colors in the feathers of a bird are determined two factors: pigment and structure. For example, the green in some parrots is a result of yellow pigments over blue-reflecting feathers. In the case of a white peacock, its unusual lack-of-color is due to a missing pigment. This missing pigment is dark and absorbs incident light, making diffracted and interference light visible (i.e. common peacocks). The effect is similar to that of oil on water.
Pigment colorization in birds comes from three different groups: melanins, carotenoids, and porphyrines. Melanins occur as tiny specks of color in both the skin and feathers, and ranges from the darkest black to pale yellows. Carotenoids are plant-based and are acquired only by eating plants or by eating something that ate a plant. They produce bright yellows and brilliant oranges. The last pigment group, Porphyrins, produces a range of colors including pink, browns, reds, and greens.
But feather structure is as important to color as pigment. Each feather consists of thousands of flat branches, each with minuscule bowl-shaped indentations. At the bottom of each indentation is a lamellae (thin plate-like layers), that acts like a prism, splitting light. It's the same principle for butterflies and hummingbirds.