Color of male and female

The plumage is an even dark brown color overall. The ornamental feathers of the male, as well as the back  shoulder and wing-arch are darker in color. Only the ornamental feathers of the male show a moderate sheen.

Down: brownish-gray.

Serious faults

Uneven in color. Too dark or too light overall. Differently colored feather-parts.

Faults

Serious faults occur to a lesser degree.

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