Blueberries are a blue fruit. They obtain their color from high concentrations of anthocyanin, which is a water-soluble pigment. Anthocyanin creates colors that range from deep shades of blue to red.
Blueberries are green when they first begin to grow. During the growth process, they turn translucent, then purple, before turning blue.
Blueberries grow to a variety of sizes. A single serving of berries is 1 cup. Blueberries do not stop ripening after harvested. They can be ripened by placing them in a bag with an apple. Apples contain ethylene, which is a colorless hydrocarbon that hastens ripening of fruits.