I am just trying to figure out who has started to lay. I have 2 black Australorps, 11 BSL and 2 buff orpingtons. I have the last 2 days been getting some small darker brown eggs and I suspect those are from the BA's.
Buff Orps lay brown eggs as well, and pullet eggs tend to be darker brown in my experience. I dunno about Australorps as I have never owned one of those. Hope that helps.
My BA lays fairly light eggs, always has. They are creamy tan, w/a yellow cast. My BA lays the lightest of my eggs. But maybe that's just my girl. My BO's eggs are darker than hers.
Well you know, I just went back to look at my egg pictures on my BYC page, and all their eggs were darker when they first started laying. So hers lightened up/adjusted over time. So it could be your BA...lol.