Initially red or pinkish immediately after the injury; it quickly turns dark blue, purple, or black as the blood loses oxygen.
Finally turns yellow-brown or light brown before disappearing completely. First Aid & Treatment Bruise healing - series—Healing, part 2 - MedlinePlus Bruises
As your body repairs the injury, it breaks down and reabsorbs the trapped blood. This biochemical process causes the bruise to change colors over roughly two weeks: Initially red or pinkish immediately after the injury;