Veins are blue in color, they carry deoxygenerated blood which
has greater absorption coefficient than the oxygenated blood that
runs in artery which is mainly responsible for the blue color.
The largest vein in the body is the venae cavae. Veins are
translucent so the color observed is the bloods color through the
fat tissue. The veins contain 60 percent of the body's blood volume
at any time.