No, blood color is not yellow. All blood in the human body is red.
While blood appears red when oxygenated due to the iron in hemoglobin (the protein that carries oxygen in red blood cells), it is never naturally yellow within the body.
There are rare medical conditions, such as severe jaundice or hyperbilirubinemia, where bilirubin levels (a yellow pigment) are extremely high, which could potentially impart a yellowish tint to bodily fluids. However, this is not the natural or healthy color of blood. Furthermore, these conditions typically affect other tissues and fluids much more noticeably than the blood itself, which would remain reddish-brown.
Deoxygenated blood is a darker red, sometimes described as purplish-red, but it's still within the red spectrum. Blood only turns yellow if certain substances are mixed into it post-collection, or in the presence of rare and severe health conditions.
