Blue

Color male and female

Upper plumage, down and shafts evenly single-colored, bright, greyish blue, each feather may show a narrow, slightly darker feather edge.

Serious faults

Completely different colored feathers. Uneven color, rust or large blackish spots. Clearly visible edging. Too dark ornamental feathers.

Faults

Partly mis-colored feathers. Too light feather color.

Genetic code: https://kippenjungle.nl/Overzicht.htm

Website with all available information regarding chicken genetics including the chicken color calculator.