Egg shell colour genetics can be complicated, particularly the brown colour, but because olive is actually a combination of brown and blue, your crosses could have blue, brown, or green eggs. DC Chick it also depends on the genetic background of your hen and rooster. The only way to be sure is to cross them and see.
The way to get olive eggers usually is to cross a blue egg layer breed with a very dark brown egg layer breed and then breed that F1 green egg layer to a dark brown egg layer breed again. the F2 cross should lay dark olive eggs.
