What color blood is healthy?

The red color of blood comes from hemoglobin in red blood cells, which changes with the oxygen content of red blood cells. Arterial blood with high oxygen content is bright red; Venous blood with low oxygen content is dark red; If it contains more methemoglobin or other hemoglobin derivatives, it is purple-black. Plasma (or serum) is transparent and light yellow because it contains a small amount of bilirubin; If it contains chyle granules, it is milky white and turbid; Red if hemolysis occurs.