There are a few different genes that can combine to produce a Blue Eyed Leucistic. Lesser/Lesser (Super Lesser), Lesser/Mojave, Mojave/Mojave (Super Mojave), and a couple others I can't recall. The super lessers can have some slight deformities like bug-eyes from what I understand. The Lesser/Mojave is generally a pure white snake without the bug-eyed problems (I own one of these myself). The Super Mojave tends to have the graying on top of the head like the one you are looking at. If I had to bet with my somewhat limited knowledge, I would guess the BEL you posted is a super mojave, but if I'm wrong someone will come along and point that out. From what I understand, that graying does not go away as they age. Personally, I find the graying looks nice as a contrast on an otherwise patternless animal, but if you like the pure-white look, I'd say try and find a Lesser/Mojave blue-eyed.