Having a wide and wonderful variety of chickens means that we get to enjoy an equally varied selection of eggs. From deep brown to bright white and even shades of blue, organic hens' eggs come in all colors and shades.But what is it that determines the color of an eggshell? We asked Sara Ward, founder of Hen Corner, to explain.It turns out that you can tell what color egg a chicken will lay by taking a close look at its earlobes."The color of a chicken's egg is determined by their breed," said Ward, who founded Hen Corner after setting up a little bit of country life in her West London home, including a flock of chickens, a flourishing kitchen garden and some beehives."I know what color eggs my chickens will lay by looking at the color of their earlobes," Ward continued. "Chickens with red earlobes lay brown eggs and chickens with white earlobes lay white eggs. Chicken breeds which have white earlobes with a pearly, iridescent shine, like my cream legbar, lay blue eggs."And, in a manner similar to mixing paint, two different chicken breeds can mate to create mixed-tone eggs. "I bred my cream legbar, who lays blue eggs, with my Orpington, who lays pale beige/pink eggs, and the results were beautiful green eggs," said Ward. "My chickens never fail to surprise me!"What about the yolk?The color of an egg yolk is determined by the hen's diet — the more greens in the diet, the deeper the yellow tone of the yolk.But this can change with the seasons, meaning that when free-range hens eat the natural greenery that grows during the summer months, their yolks are a deeper yellow color. When they rely more on pellet feed in the winter months, however, their yolks are a paler color.Ward saves her favorite eggs and cleans them.The lowdown on hens' eggsDark brown eggs come from hens with red earlobes Example breed: Coucou MoranWhite eggs come from hens with white earlobes Example breed: White leghornPale beige/pink eggs come from hens with white earlobes Example breed: OrpingtonBlue eggs come from hens with white/pearl earlobes Example breed: Cream legbarWhy do brown eggs cost more? The brown color gets deposited in the hen's uterus as the last part of the shell-making process. White eggs simply skip this part of the process. So why are brown eggs more expensive? "The brown egg layers need to have more nutrients and energy in their body to produce an egg than the white shell layers," Deana Jones, a research food technologist at the U.S. Department of Agriculture, told Huffington Post. “It takes more feed for a brown-shell egg layer to accommodate production of the egg," Jones said. It's important to note, however, that there is no nutritional difference between white eggs and brown eggs.