This is what I have found doing a google search. I found it HERE <---Klick
Shell
Main article: Eggshell
Egg shell color is caused by pigment deposition during egg formation in the oviduct and can vary according to species and breed, from the more common white or brown to pink or speckled blue-green. In general, chicken breeds with white ear lobes lay white eggs, whereas chickens with red ear lobes lay brown eggs.[15] Although there is no significant link between shell color and nutritional value, there is often a cultural preference for one color over another. For example, in most regions of the United States, chicken eggs are generally white; while in the northeast of that country and in the United Kingdom, they are generally light-brown. In Brazil and Poland, white chicken eggs are generally regarded as industrial, and brown or reddish ones are preferred.