Most people never give a second thought to eggshells as it is what is inside the egg that is the most important part. We only eat the yolk and the albumin of the egg and we waste the eggshell.
However, it is worth giving more thought to the eggshells of hen’s eggs as they use a lot of calcium in order to make it hard, strong, shiny, and, in some cases, colorful.
The most common color of eggshells is white but some hens lay brown-colored eggs. That being said, there is a wide range of variation in the color of eggshells. Some of the more elaborate eggshell colors include gold, dark brown, chocolate, pink, blue, olive, or green.
If you have ever seen strangely-colored eggs, you have probably wondered what kind of chicken they come from. This article will answer any questions you may have about hens which lay green eggs.
What gives chicken eggs their color?
Before discussing chickens that lay green eggs, we need to look at the reason behind shell pigmentation. As mentioned earlier, white is the most common color of chicken eggshells. Did you know that blue is actually the original color of hens’ eggs? The main reason behind the color in hen’s eggshells is the pigment that the hen secretes when the egg is still in the oviduct.
Eggs start off with white-colored shells and as it travels through oviduct, a pigment known as oocyanin is secreted by the glands and this penetrates the eggshell. This pigment not only makes the outer shell blue, but it also stains the interior of the eggshell. With brown-colored eggshells, the oviduct secretes a pigment known as protoporphyrin, but this only happens later on and only changes the outer color of the eggshell. The pigments that the oviduct secretes will vary from species to species and this is the reason for the different-colored eggshells.

What makes eggshells green?
Some hen species secrete layers of pigments that give different colors to shell. In the case of green eggs, their original color is actually brown. This brown color is overlaid by a blue pigment that is olive or green in color. The protoporphyrin pigment is overridden by the oocyanin pigment in the case of green eggs. The darker the protoporphyrin pigment, the darker green the eggshell will be.
Chicken breeds that lay green eggs.
Now that you know about the reason behind the green eggshell color in certain species of chicken, we will now discuss the various chicken breeds that lay green eggs. There are four cross and pure-breed chickens that lay green eggs and we will discuss all four of them.
Isbar
One of the pure-breed chicken species that lays green eggs is the Isbar. This breed was developed in Sweden specifically due to their different colored eggs, although it mostly lays green-colored eggs. The standard color of this chicken’s eggs is green but it sometimes lays eggs with brown spots due to a lack of sufficient overlaying of the blue pigment. One of the most important facts about this breed is that you can easily differentiate between gender at the time of hatching. This characteristic is called as auto-sexing. The isbar chicken is a rare breed and is not present in all countries.

Easter Egger.
The Easter egger chicken is not considered to be an actual breed of chicken as a number of hens are crossbred to obtain this species. These crossbred chickens produce eggs with blue and brown layers, resulting in medium-sized green-colored eggs.
Favaucana
The favaucana chicken is a crossbreed between Faverolles and Ameraucana. This chicken is genetically programmed to lay green eggs. The faverolles chicken produces light brown colored eggs, while the ameraucana chicken lays blue colored eggs. The Favaucana chicken will therefore produce green eggs. It is possible to crossbreed these two hens to get a Favaucana chicken, as long as you take certain measures. The favaucana chicken is an easter egger breed.

Olive egger
Olive egger chickens are also a type of easter egger chicken that have been specifically crossed to achieve dark olive-colored eggs that have a green appearance. They lay blue eggs which have a layer of brown tint appears green in color.
Hopefully, you now know more about chickens that lay green eggs and why this happens!