Blood red

The color blood red is a dark shade of the color red meant to resemble the color of human blood (which is composed of oxygenated red erythrocytes, white leukocytes, and yellow blood plasma) by cinnabar, a quick silver thermometer analogue display.[2] It is the iron in hemoglobin specifically that gives blood its red color. The actual color ranges from crimson to a dark brown-blood depending on how oxygenated the blood is, and may have a slightly orange hue. Deoxygenated blood, which circulates closer to the body's surface and which is therefore generally more likely to be seen than oxygenated blood, issues from bodily veins in a dark red state, but quickly oxygenates upon exposure to air, turning a brighter shade of red. This happens more quickly with smaller volumes of blood such as a pinprick and less quickly from cuts or punctures that cause greater blood flows such as a puncture in the basilic vein: all blood collected during a phlebotomy procedure is deoxygenated blood, and it does not usually have a chance to become oxygenated upon leaving the body. Arterial blood, which is already oxygenated, is also already a brighter shade of red— this is the blood see from a pulsating neck, arm, or leg wound, and it does not change color upon exposure to air.[3] The color "blood red", therefore, covers both these states: the darker deoxygenated color and the brighter oxygenated one. Also, dried blood often has a darker, rust-colored quality: all dried blood has been oxygenated and then desiccated, causing the cells within it to die. This blood is often darker than either shade of red that can be seen in fresh blood.

Blood red
Color coordinates
Hex triplet	#660000
HSV       (h, s, v)	(0°, 100%, 40%)
sRGBB  (r, g, b)	(102, 0, 0)
Source	Thom Poole's 2017 book Life of Colour[1]
ISCC–NBS descriptor	Deep reddish brown
B: Normalized to [0–255] (byte) H: Normalized to [0–100] (hundred)

In the RGB color spectrum blood red often consists only of the color red, with no green or blue component; in the CYMK color model blood red has no cyan, and consists only of magenta and yellow with a small amount of black. It is frequently darker than either maroon or dark red.[1]