Any "Mutation" is based off a change to the Ancestral bird.
You have to understand the reason for the visual changes/mutations to the birds.
GREEN - Has psittacin
BLUE - No psittacin
PARBLUE (Turquoise) - Partial psittacin
Breeding "Blues" to "Greens split to Blue", you will get Greens with Psittacin, and Blues with no Psittacin. There is no way to achieve PARTIAL psittacin through these pairings.
The same for "Green to Green", and "Blue to Blue". All babies will either have it (Green), or not (Blue).
Unless you are one of the very, very, very rare people (like 1 in a billion) who gets a mutation to occur naturally in your flock, you have to have a Parblue to produce one.