Whos laying brown egg with purple specks?

[CTompkins]

I cannot figure out for the life of me which Chicken is laying this Egg. I thought it was my light Brahma, but she just laid a brown egg with a white overcast. I’m at a loss. I’m trying to hatch some baby Brahmas, but I cannot figure out which egg is which.

 

[nuthatched]

Unfortunately, this isn't a bred specific trait.