When a bruise is brand new, it will appear reddish due to the color of the blood that leaked from the capillaries under the skin.
At one to two days old, a bruise will take on a bluish or purple color. The swelling at the site of the bruise will cause oxygen to be cut off, and hemoglobin, the substance that carries iron in your blood, will turn blue.
At six days old, a bruise will turn a greenish color as the hemoglobin breaks down and the area begins to heal itself.
At eight to nine days old, a bruise will then turn yellow or brown. This is the final stage in the body’s re-absorption of the blood.