That's true, Wisher, but color is often in the eye of the beholder. There is a wide range of colors covered under "blue". A look at the ameraucana color chart shows a range from what I would call grey to what I would call teal. They are all technically considered to be blue by ameraucana egg standards.
Now, I'm with you. When I look at ameraucana eggs I want to say "Wow! What a pretty BLUE egg!", but that's not always what you get. To make it even more complicated, given the individual genetics of humans, we don't actually "see" the same colors when we look at stuff. Over years of childhood training we have learned to call certain frequencies of light by the same name. But we most certainly don't "see" the same thing since our brains are all a little different from each other and color is merely an interpretation of electromagnetic frequencies.
I have pure ameraucanas bought from people high in the Ameraucana Breeders Club. There is no doubt that these babies are pure as the driven snow and have long pedigrees. When my hens first started laying I fired off a cranky email to the breeder asking why the heck these PURE ameraucanas were laying GREEN eggs. I was told that most breeders were working on confirmation of the bird and most didn't care about egg color. Thus most eggs would range from green to blue. Sigh. To make it even more fun, I had ordered eggs from the breeder known to have the bluest of the blue eggs. When they got here they weren't near as blue as the photos had shown. I set them anyway, hatched out a couple of hens and started using them in my breeding program. Turns out that the hens did lay a beautiful sky blue eggs, but all of their offspring had red and gold leakage problems in their feathers. I ended up having to sell off an entire season of chickens and start all over again.
I have recently discovered that even pure ameraucanas can potentially not be homogenous for the blue egg gene. Apparently some AMs carry two blue egg genes and some only carry one. Since the blue egg gene is dominant, you wouldn't know unless in your breeding you run across another AM not homogenous for the blue egg gene. ARGGG! The whole deal is fraught with peril. I have recently been told that there are at least 13 genes that control egg color. There is a high chance for chaos.
That being said, an ameraucana has to lay blue eggs to be an ameraucana. If they don't lay some shade of blue or blue-green then they are an easter egger. If they don't fit the accepted color patterns used by the Standard of Perfection, then you have an easter egger. Once you are absolutely sure that it is the "ameraucana" laying the brown egg you should get back in touch with the breeder and question them. Either there is a flaw in their breeding program or they have sold you an easter egger.
Was this breeder a member of the Ameraucana Breeders Club? That doesn't quarantee anything, of course, but it gives you a fighting chance of actually getting a true ameraucana.
