Ever since I learned that eggs could be blue and green, I’ve become obsessed with collecting as many different chicken egg colors as I can. It brings me so much joy to see a colorful collection of eggs.
Eggs shells are primarily calcium carbonate, which is white. There are 3 main ways eggs obtain their color: mixed in with the shell structure, coating the exterior of the shell, and the bloom protective layer.
Some chickens carry a gene that causes them to mix the pigments oocyanin or biliverdin while forming the eggshell, giving the eggshell a blue and/or green tone. The pigment is all the way through, and you can see it on the inside of the shell. In my experience, the hue and color intensity are consistent in individual hens. Unlike with brown eggs, the eggs don't seem to be noticeably darker after a break. I wasn't able to capture the difference very well in these pictures.
Some chickens carry genes that make them deposit the pigment protoporphyrin on the exterior of the egg, turning the outside of the egg brown. It can be scratched off, and the inside color of the egg is not supposed to be affected. However, my brown laying chicken's eggs are never pure white on the inside.
Different chickens have different intensities of brown. Welsummers tend to have spotted eggs, due to clumping of the pigment. Black Copper Marans tend to have darker eggs, due to more pigment production. When hens lay eggs more quickly, the brown color tends to be diluted. In the pictures below, my BCM is at the end of her 6 days of laying eggs in a row, and the eggs will be darker after a break. My Wellsummers never seems to get much darker than this.
The bloom or cuticle is a protective layer the chicken adds to a completed egg to seal it from bacteria. This layer will provide a red or pink tinge and slowly degrades overtime. Unfortunately, I wasn't able to capture the pink color very well in this picture on the left. In the US, commercial eggs are washed to remove bacteria which also removes the bloom. This is why store-bought eggs don’t have reddish or pinkish tinges, and also why you have to refrigerate eggs. Most other countries do not mandate washing eggs, and they are sold and stored at room temperature.
There are also white spots, but I haven‘t found out yet how those happen.
Mixing these genes gives a whole host of different colors, like mixing blue, brown, and pink paint. My sage-colored egg is blue/green with a light dusting of brown on top.
I've found the following colors on the internet: Olive, Olive with spots, Plum, Pink, and Gray. I'm going to try to catch-em all!
