What attributes tell you that it's a Jersey Giant, and not an Australorp?
I'm asking because I have two girls that look like this. Guy told me they are Australorps, but they just don't look it.
Foot color should be yellow on the bottom for JG, Pink for Australorp. I have JGs, and understand that the two are very similar. My two oldest hens looked like that one day, and then had big combs the next. Mine have the softest feathers in the flock and a great blue/green sheen.