Hen lays blue eggs, suddenly lays grey eggs?

[McChooky]

A brown egg(Not talking olive though), can have brown pigmentation inside the shell to on occasion under the membrane. Sometimes it's pigmented all the way through rather then painted on.View attachment 3970125

I've heard the brown egg gene only tints the outside whereas the blue egg gene goes all the way thru.Interesting fact for breeders

 

[EmmaDonovan]

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I have 5 generations of gray egg layers.
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People don't wash a black copper maran egg before taking a pic. So enjoy that gray egg. (Also there are 2 kinds of eggs. Matte- which has heavy bloom, and glossy.)
I will admit this purple egg below was bloom. I wish I had more pics of it, if you have a neat egg, get lots of pics.
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Those are gorgeous!