Taxidermic White Peacock. Pavo cristatus.  Photo Bonhams

An albino peacock is a type of peafowl, distinctive for its pure white color due to total or partial lack of biochromes. Often incorrectly referred to as an "albino peacock", it is nothing of the sort: albinism, would cause lack of pigmentation not just in the feathers, but in the skin and eyes as well. A white peacock is, technically, 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 specs 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. 

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 which are lamellae (thin plate-like layers), that act like a prism splitting light--with the same principle for butterfly wings and hummingbirds.