Yet a glance at the older studies of the color of venous blood shows the difference between these investigations and the subsequent intuition. However, a culprit for this discolouration is haemoglobin, a protein which is found in erythrocytes. Pin On Nursing Blood color brightness was measured using a blood brightness scale (bbs). What color is venous blood . It owes its color to haemoglobin, to which oxygen binds. However, technically, that is completely inaccurate. Arterial blood (apart from the special case of the pulmonary arteries) is fresh from the lungs & full of oxygen so has a bright red colour. Veins take blood into the heart from the body organs. Vital spirit and pure air according to classical tradition, venous blood is produced in the liver through the process. Venous blood is lower in oxygen & has a higher concentration of carbon dioxide and has a dark colour. Bd vacutainer venous blood collection tube guide wall chart. The venous blood is bl...