Twitter is a paler yellow than my other pied, and the 'green' is a very soft grey-green. Very pretty even with the new feathers sticking out everywhere!

 

 

 

Twitter is a young bird - the colours will darken/get stronger with his first moult.I would lean towards saying he is a grey-green as the one bit of cheek patch not affected by the pied gene doesn't look dark blue but more grey blue.