Cute and getting big.
They're beautiful, I need some in my life.
How old? My female BCMs usually don't show copper as quickly as the males.
I don't have any Blues so don't research them too much other than hatch down color to identify, but I do notice the hackles are usually much darker than the body color. I'm not sure why this is? And if that has an effect on the copper appearing or not appearing. But if these are hatchery stock, I wouldn't expect much copper to appear just like in a lot of Black Coppers being sold as they're not actively setting up their breed groups focusing on full hackle copper like breeders do. None of my original stock has full hackles, I didn't start getting them til I paired Kong up, who's over colored in the chest.
Maybe
@BlueTheBrahma can shed more light on the Blues for us both.