questions about egg colors...changing colors?

The color of a hen's eggs will lighten towards the end of each laying cycle, but it is unlikely if not impossible for color to change.

I have an EE that has been laying since January and started with a dark olive color egg that is now light green.  I also, have another EE, who laid a powder blue egg and now it is light light gray, almost looks white until you hold it up to a white egg!

There is a gene that controls whether the base egg color is blue or white. Since blue is dominant, if just one blue gene is present, the egg will have a base blue color. Otherwise it is white. You can see the base color when you crack the egg. Just remove the membrane and look at the inside of the egg shell.

The brown and green come from other genes. There are a lot of different genes that control the brown. How they go together determines the shade of brown. If no brown is present, the egg color will be the base color of the egg, either blue or white. If brown is present on a blue egg, the egg will be green. If brown is present on a white egg, the egg will be brown.

Base blue + no brown = blue
Base blue + brown = green
Base white + no brown = white
Base white + brown = brown

As a hen lays over time, she uses pigment in her body to make the brown. This is really noticeable in a yellow-skinned chicken. Over time the legs, vent and various yellow body parts lose their color and can become almost white as that pigment is used up. Right after a hen molts and starts laying again, her eggs will be as dark brown as they ever will be. The longer she lays, if she is a good layer, the lighter her eggs will be. I've had brown egg layers go from a nice brown to almost white egg just before a molt.

That's probably why your green egg is getting lighter the longer she lays. When she molts and restores the pigment, the egg should get a darker green.

I don't have an explanation for blue egg becoming a lighter blue, just why a brown or green egg will become lighter. It's her using up her pigment.

maybe her first eggs weren't getting alot of pigment laid over them, now she is producing more pigment coloring the outer layer blue to brown? See if any of the brown eggs wipe off to reveal blue-but it really should have turned green. So maybe the blue went lighter and now looks more white?