Here you go:
"Hormonal blue" - When some females from some localities (or races if you prefer) develop follicles or ovulate (depending on the individual), they eliminate the xanthophores (spelling?), that is the yellow pigments. As a consequence, the green becomes blue (Green - Yellow = Blue) and the yellow becomes white. Usually, a couple of months after the egg deposition, of if the follicles are reabsorbed (in this event, they don´t ovulate) they go back to normal.
After 3 or 4 pregancies, some females remain blue for the rest of their lives. Others don´t.
It is not an inheritable trait, although the daugthers of hormonal blue females are more prone to become hormonal blue as well.
This occurance happens more frequently with females from the Aru Island but also with some mainland localities (Sorong, Jayapura, Manowari, Cyclops Moutains, etc) and, to some extend (more grey than blue) with Biaks.
"Ontogenic blue"- It is an inheritable trait thus ocurring with males and females. The GTP´s simply become "BTG"...
Blue GTP´s may be "true blue" or "super blue":
a)true blue - they go from maroon/red/brown (there are no records of blue snakes coming from yellow neonates so far) to green and later from green to blue.
b) super blue: they go directly from maroon/red/brown to blue without a "green fase". These are - obvisouly - the more sought after because they have an extremely high possibilty of only having blue kids.
Hope this clarifies
Regards
Joao