Perennial Hill, LLC

Colorful Eggs

The genetics that determine the color of chicken eggs are very complicated, and there is still a lot that is unknown when it comes to depth of color, speckling, and bloom.

In a very simplified understanding, every eggshell is either white or blue, and that is determined by two genes. The gene for blue shells is dominant, so if a hen has one gene for blue eggs and one for white, she will still lay blue eggs. Blue eggs are not just made of calcium carbonate and other minerals found in white eggs, but also have oocyanin throughout the eggshell, which makes it blue.

What about all of those brown eggs? There are at least thirteen genes that control the level of protoporphyrin, or brown pigment, that a hen’s body may coat a white egg with, and this is how we get tinted, cream, brown, chocolate and everything in between. We think of this as “brown paint,” and we’ll refer to it here as simply “brown paint.”

If a hen lays blue eggs and also produces brown paint, then she will lay eggs that appear green. How strong the blue pigment and how dark the brown paint is will determine the shade of green.

What about gray, purple, and pink? Every hen coats each egg with a bloom (or cuticle), a mucous coating that protects the egg’s precious contents from bacteria. Often the bloom will dry clear, however, some hens have a heavy or thick bloom that appears white. This heavy bloom can make a light brown egg appear pink, a dark brown egg appear purple, and green egg appear gray.

Speckling is even less understood than the factors influencing bloom. Raised speckling is often thought to be excess calcium deposits that the brown paint or bloom gets caught on, and flat speckling is thought to be a misfire or error in the brown or bloom coating process. Much of the research surrounding speckled eggs focuses on how to eliminate the occurrence of speckled eggs, as industrial egg farms want to produce eggs that are virtually identical.

So there are white or blue eggs, varying levels of brown paint (with possible speckling from paint splatter), and varying levels of clear to white bloom (with possible speckling from bloom splatter) that produce the wonderful variety of colors.

Any step of the egg creation process can be influenced by the hen’s diet, environment, age, and the season. A hen may not lay an egg with the same color, speckling, or bloom on a consistent basis. Bloom can be washed off (as seen in the wet egg photo above), and brown paint can be smudged while it is drying after the egg is laid. Dried brown paint can also be sanded off to get down to the underlying white or blue eggshell color.

Silverudd’s Blue & Our Gilded Martin Project

Silverudd’s Blue (named for its feather coloration) should lay green eggs. The inconsistency in the brown paint over the blue egg, as well as variety in speckling, produce a wide variety of greens. The breed, twice imported to the US by Greenfire Farms, was unfinished at the time of Martin Silverudd’s death. The breed was not refined enough to lay 100% green eggs. The first import included some birds that only had one blue egg gene, leaving the possibility that a hen could inherit two white egg genes, and lay a brown egg. If you want Silverudd’s Blue and have high expectations, we always recommend working with a small breeder who is undertaking the arduous work of breeding Silverudd’s Blue that carry two blue egg genes and appropriate brown paint, follows the breeding guidelines from the breed association, and mostly works with first import breeding stock (second import stock is believed to have more variability in all attributes and be further from the ideal Silverudd’s Blue). We are offering Silverudd’s Blue chicks in 2026, but do not claim to have top or breeding quality birds.

The inconsistent genetics in Silverudd’s Blue may explain why it has not been used widely in Olive Egger (not a breed, but a name used for any chicken that has a blue egg gene and dark brown paint) breeding. The consistent blue egg genes of the Ameraucana and dark brown genes of the French Black Copper Marans are most often used to create an Olive Egger. To achieve a dark olive egg from a typical Olive Egger cross, breeding often involves successive generations and some level of backcrossing or filial breeding to get a deeper brown paint, and in the process also produces a lot of hens who just lay brown eggs since they don’t inherit a blue egg gene.

Is there a shortcut? A hen beat us to testing out French Black Copper Marans x Silverudd’s Blue when she squirreled away some eggs and insisted she was going to hatch them. When another followed suit, we decided to let them do the work for us. The egg colors from their offspring are wonderful!

Both Silverudd’s Blue hens who produced the offspring laying these eggs are from Greenfire Farms. The mother of the hen laying the first two eggs lays an almost blue egg. She has little to no brown paint and typically has a heavy white bloom on her eggs. The mother of the hens laying the bottom four eggs lays a consistently green egg, sometimes with a white bloom. (Silverudd’s Blue should always have enough brown paint to make their blue eggs appear green, and white bloom is undesirable for Silverudd’s Blue since it risks the eggs not appearing green.)

2026 (Expected) Egg Colors

Updates coming soon – blue egg gene tests pending!

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Our Breeds & Breeding Projects

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