The colour must be as uniformly grayish blue as possible. In reality, however, we see how the cock’s neck and saddle hackle are a shade darker. Some more faults one comes across in blue specimens is some brown staining called rust, or black splashes of uneven colour intensity.
The blue colour is not homozygous. By mating a blue cock to a blue hen the offspring will be about 50% blue, 25% black and the last 25% splash. By mating black to splash the offspring will be 100% blue.
In the Netherlands, blue is seldom seen in Leghorns of both the standard and bantam varieties.

Additional information