Lavender 

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, genetically characteristic are very narrow transverse accumulations of pigment. These stripes are darker in color than the rest of the feather, the aim is to achieve color uniformity.

The darker tinted transverse stripes are not considered a fault if present to a limited extent.

Down: silvery pearl grey.

Serious faults

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

Faults

Slightly too light or slightly too dark color. Some slight yellow glow in neck- and saddle-hackle, shoulders and back of the male. Many dark tinted transverse stripes that negatively affect the image. 

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

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