What cells give human blood its red color?

Iron & Hemoglobin: Hemoglobin is the protein that contains 4 atoms of iron which can bind 4 atoms of oxygen. When this happens, the hemoglobin changes shape such that its absorption of light is different and appears more red. However, even if you're anemic, regardless of iron status, your blood will still appear red due to the minimal amount of iron, although you may physically appear more pale due to less blood.

Red blood cells: It's the red blood cells that give blood it's red color. The more oxygen the cells carry the brighter red the blood. Blood from an artery is high in oxygen and is very red. Blood from a vein hd less oxygen and is dark red.

Hemoglobin : Hemoglobin which contains iron gives human blood cells their res color.