Color and pattern male and female

Plumage: evenly medium-colored slate blue; each feather dark blue-black laced. Hackles appear darker blue.

Down: slate blue.

Serious faults

Complete or partial white, black or other colored feathers. Too dark or rust-colored blue. Missing or too unclear defined lacing.

Faults

Serious faults to a lesser degree.

Feather details from:  http://www.kippenencyclopedie.nl

Website from Johan Albada with more than:

         5000 photos of chicken-breeds, chicken color varieties and feathers.     

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