From the pic I would think cobolt. Too light for mauve(I have a few mauve) and too dark for sky blue. His color may change slightly if the yellow continues into the belly after the next moult. I can see why you say mauve though. Maybe another pic will help.
No worries. The powers that be will check the genetics threads when they come on and give you a more definite answer. More pics will help. I am really interested to see the answer on your little guy too. He is really stunning.
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"The best things in life are not things."