The Different Colors of Blood

If the blood is carrying oxygen it's a really, really bright cherry red and if it's already delivered its oxygen it's still red but it's a little bit darker. If I look at the inside of my wrist I can see some blood vessels and it looks like they're blue or purple so you might see it in your inner elbow too. The reason that we see our veins as either blue or purple or even green in some people has to do with the color of our skin.