Well to me, the blacks look black and the blues look blue. I don't have any suggestions except to say if I had to know early on what they were, I would put the black chick up against a black from a 100% black pairing and try to note any differences as they mature until you can tell. Then keep that in mind next hatch and see if the same happens.
I have nothing on the blues, except to say I would be shocked if they turned out black.
I would love to see a pic of your mature black (blue) chicks though. I think I saw a pic of one of your blues once and she looked great. Was she a black chick?