Blue Plymouth Rock?

[Chookmama72]

I have a pullet female with dark coming down on her legs as well and she was sold to me as a BPR, so now I'm wondering if she's not and maybe a australorp instead. She's a gorgeous dark gray with a darker head and hints of blue-gray on her belly. I don't have internet at home and am at my hubby's office on his PC so can't show pics, but can anyone clarify about the leg coloring?

 

[_-Captain BRM-_]

Looks like sapphire gem. They were made by a cross with a blue Plymouth I believe... Or maybe blue Plymouth and sapphire gem are the same bird? I can't remember