Red Pencil Rock? Is that a type of breed?

[clrdogrl]

Someone is selling red pencil rock pullets and they are supposedly a variation of the partridge rock...like a lighter red. Here's a couple pics of the pullets that are 12 weeks old. Does the penciling show up when they are older or should all their feathers be penciled in this age? Or maybe this is just the difference between some partridge rocks being light and dark?
In the first picture, I'm referring to the pullets in the background.
Is the plumage just not fully grown in yet or is this what she will always looks like?