Yes, I agree that it is a cockerel. Those white shoulder patches are a strong indicator in laced Wyandottes of a cockerel. Usually the comb would be big and red, but they all develop differently.
The color pattern isn't ringing any bells. It may be one of the designer hybrids offered by the hatcheries. When it feathers out it may be easier to tell.
The main point of Sapphire Gems is that they are sex linked. Males should have barring, and your chick does not. So it should be female.
I think the problem arises when other breeds are accidentally purchased or substituted for SGs. It is difficult to tell solid colored blue chicks of different...
Make sure it is getting enough to eat. I would give it some meal worms or boiled egg yolks to see if that helps. It is probably failure to thrive because the chick is much smaller than the others, even accounting for differences in breed size. That doesn't mean it can't recover, though.
If the feet are yellow then they probably are SGs. Hatcheries do sometimes make mistakes, and sometimes they just substitute different breeds. It is my impression that they have white earlobes, but I am not 100% certain. It will take several more weeks to be sure of that. Maybe 12 to 14 weeks.
Looking closer, I think those might be Andalusians instead of SGs. That could explain why the one looks raptor-ish. The pigment on the feet appears white, not yellow, and I believe these will have white earlobes. So the first blue one could be a cockerel. Time will tell.
I think they are all females. If the barred birds are definitely barred Plymouth rocks, then they have to be females because all are single barred, not double barred as males would be.
The first one actually is quite pale, but the green wash on the legs is another female trait in barred rocks...