The photographer and owner of that animal have said that the animal was not really blue. It just came out that way in the picture.
You're going to have a number of other people post here claiming to have a blue Crested or one with blue on it, but what they're talking about is a grey color with no olive pigment...which I guess might look "blue-ISH" if you tilt your head to one side, squint your eyes and hold your breath for five minutes.
I have several animals with that coloration and I've had the pleasure of looking at other peoples' supposed "blue" Cresteds and I can tell you first hand that they're not even close to the blue that you see in that picture.
Some way, somehow, herpers are notorious for seeing colors that they really want to see in their animals. 
-Anthony
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Anthony Caponetto
www.ACreptiles.com