Hi Tazcat,
Pullets will typically lay the darkest eggs but it varies alot. For instance, my first eggs were actually kinda pale. Not too bad, but not what I was looking for. Then, they started getting darker. Afer they have been laying for a while the color will get lighter again. If they take a break, even for a few days, the color darkens right back up again. One reason for this is that, unlike typical brown egg layers, the pigment in a marans egg is actually laid down on top the the shell at the very end. This color can even be washed off with just a bit of scrubbing. It is even more delicate when the egg is still moist right after laying and I learned this hard way. While trying to figure out which of my hens were laying what, I would try to catch them while still on the nest. One day, I found a hen on the nest about to lay. I saw her drop the egg and then she rested a bit. Once she got up I saw the egg and it appeared dry but when I picked it up there was a tiny bit of moisture left on the egg and I wound up putting a nice finger streak down the egg. It was a really dark egg that would have been perfect for the egg contest I was entering too. I was so mad!!
Richard