Blue eggs are blue all the way through, but brown eggs are only brown on the outside! Brown eggs get their color from a pigment called protoporphyrin, applied near the end of the egg development process, almost like a natural coat of paint that colors only the outside. Blue eggs, on the other hand, owe their tint to oocyanin, a pigment added earlier that soaks through the whole shell, turning both the inside and outside that lovely shade of blue!
