Ahh, sorry, sometimes pics never do Guinea colors justice, so I was going by what I could see from the pics.
I'd have to agree, since she has the charcoal grey/black based flank feathers that she is a Bronze, with good strong Bronze genes. I have seen only a few with this much Bronze coloring before, and they are usually Hens. So they are out there, just not that many. And my guess as to why the (highly bronzed) Bronzes just aren't all that common is due to there normally being so many mixed colors in backyard flocks that are penned/housed/free ranged together and breeding freely, not separated by color which results in the dilution of the coloring (same with the nicely dark colored Chocolates, which I am working on breeding more of). I also believe that diet can and does play a huge role in the color intensities of all Guinea colors (just like with all types of poultry)... a penned bird fed a diet with too much corn in it won't have the brilliant coloring that a well fed bird that's allowed to supplement it's diet with plenty of free ranging will.
Nice Hen, hopefully you have a decent Bronze male to pair her up with and are able to produce offspring with good strong Bronze genes as well.