That's what my reaction too when I first bought and eat blueberries from supermarket. I thought because they were called blueberries, they will really color blue. But I was wrong with my perception, they are blue on the outside but deep red on the inside. That is why when I make smoothies, they will turn into deep red because of the blueberries I added. I like the color though instead of being really blue. They were just called blueberries because of the skin color its a deep or dark blue color. I like blueberries in the kitchen because of their versatile when cooking or baking. Apart from blueberries, there are many types of berries and some of them being name by their color except I think from strawberries. They are good antioxidants and Vitamin C.