Black Shoulder chick - any neck color at 12 weeks?

[old biddy]

I have a black shoulder chick that is almost 12 weeks old...I don't have a photo of it, but can tell you that it has no blue or green color on its neck, even though my India Blue chicks both have green color on their necks at 12 weeks. Does whether or not there is blue/green neck color of a black shoulder chick at 12 weeks old indicate sex of chick?

 

[Dany12]

https://peafowlimagedatabase.weebly.com/peachick-images.html#

 

[KsKingBee]

All we need is a close up pic of the shield.