Color male and female

Lavender is not to be considered a lighter shade of the common blue, it clearly differs from it, also genetically. It is of a softer, lighter and more very lavender shade without a tendency to form darker blue or bright blue in some feather groups or feather parts.

The plumage is solid color lavender, Very narrow transverse pigment bars are genetically characteristic of lavender. These bars are darker in color than the rest of the feather, the aim is to achieve color uniformity, they are not considered a fault if present to a limited extent.

Down: silvery lavender.

Serious faults

Different colored feathers. Clearly visible yellow or rust-colored deposit or pattern in the neck-hackle. Dark tinted feather-veins.

Faults

Slightly too light or slightly too dark color. Some slight yellow glow in hackles, back, shoulders and wing-bows of the male. Many dark tinted transverse stripes that negative affect the image. 

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