Blue, and lavender, are genes that cause a dilution of the black color in chickens. Therefor, they really are just shades of grey. Kind of like how they have "blue" and "lilac" colors in cats, dogs, rabbits, etc. It's not the bright colors but rather a shade of grey with a hint of that hue. However, pictures really do have a hard time capturing the true color. I really didn't think lavender was all that pretty a color when all I had to see of it was pictures here on BYC. But once I went to a show and saw actual lavender chickens I do have to say that it is quite pretty and none of the pictures I've seen do it justice at all. Yes, they're "just" grey chickens, but they really do have a hint of purple to them in real life.