Having a lesser / mojave BEL myself, I can say that she started out very pure clean white as a hatchling but has now developed yellowish color to her along the spine. She just doesn't look as clean as she used to. I also own a Russo White Diamond BEL. She came to me as a hatchling with a pale yellow line running down her spine, and at two years of age it is still there. From what I hear, that is just how White Diamonds are. If I ever get another BEL, I want it to be a super lesser / super butter, because they are known to be the most clean and pure white type of BEL.