Color male and female

Upper plumage green-glossy black, down dull-black, lighter down-color is permitted in yellow-legged breeds.

In some breeds, a steel-blue sheen is exceptionally required or at least permitted.

Serious faults 

Absence of any sheen. Off-colored feathers or red in the ornamental feathers. Strong violet tint in the ornamental feathers or white in the down.

Faults 

Low sheen in the ornamental feathers. Small off-colored spots. Slightly too light down-color, unless this is specifically permitted. 

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

Website from Henk Meijers with all available information regarding

chicken genetics including the world famous 

Chicken Color Calculator