Maybe the structure of the feather plays a role, ie, the "pearls" (in birds genetically pearled) appear different white in relation to surrounding white feather because that part of feather reflects/absorbs colour differently?
Hi Bemba
Great photos thanks. Your birds are looking beautiful & healthy, really makes a difference free ranging I, like quite a few others here are finding the rhetoric by one or two about our Cinnamon birds being product of Z-linked factor incorrect, but of course more testing to be done...