You got a gazillion times more experience than I do. I’m so clueless that I don’t even know enough to guess barred or mottled. Other than Sapphire Gems, (already blue when hatched) I’ve only raised one blue chick to adult. That was in my first batch of BCs. I can’t remember for the life of me what she looked like, but she’s a great mama!Don't know.
Possibilities are mottled black, mottled blue, barred mottled black, barred mottled blue.
What do you think? Blue? Lack of any real color on head may mean barred so I'd guess barred mottled blue.