Genetically there are three egg colors; brown, white, and blue.
All other "colors" are a mixture or shades of one color. Brown is kind of a layering of color added to the shell after it is formed. Blue and white eggs are formed blue or white.
Haha. Chicken boy was kidding guys. There are many shades of eggs though. I don't think anyone has counted them before, it would be quite hard, unless you had an egg from every chicken in the world.