I've got eggs!

I've got 7 eggs in 3 days. I haven't been able to sit and watch them like normal but how do I know which ones have layed? I have one Columbian rock with a icky looking that I have seen get up from the nesting box so I'm sure she has but how do I know about the others? I also plan on washing her off the see if the ickiness will go away. Some of my eggs are small golf ball size and I have gotten some that are bigger. Some are also darker than others. Thanks!