Color. The color of human blood ranges from bright red when oxygenated to a darker red when deoxygenated. It owes its color to hemoglobin, to which oxygen binds.

Why is my blood a dark red color?

Hemoglobin bound to oxygen absorbs blue-green light, which means that it reflects red-orange light into our eyes, appearing red. That's why blood turns bright cherry red when oxygen binds to its iron. Without oxygen connected, blood is a darker red color.

What type of blood is dark red?

Oxygenated (arterial) blood is bright red, while dexoygenated (venous) blood is dark reddish-purple.