Cayuga crossed on blue egg layer- do you get a slate grey egg?

[WhisperingOaks]

I am interested if anyone has tried crossing the Cayuga on a breed that lays a good blue egg- I think a black runner Cayuga cross would lay beautiful eggs and be a good forager. If anyone has done this cross what do the eggs looks like?

 

[learycow]

Cayugas can lay cream or green eggs. The black "bloom" disappears as the laying cycle progresses.
In order for them to lay green or blue eggs, they must have 2 copies of the gene. So crossing a white egg laying cayuga with a green egg laying runner won't give you green egg layers unless the cayuga carries the gene.
It doesn't mean the eggs the offspring lay will me a mix of the colors like you are suggesting