In maximum situations, the dark circles under the eyes are blood vessels that can be witnessed through the skin. The skin periorbital skin is the thinnest skin on the body. Just like varicose veins, dark circles beneath the eyes are generally an inherited sign. When blood flows through the large vessels close to the surface of the skin, it can produce a bluish hue. The greater the transparency of the skin, the more saturated the blemishes seem. In people with a deep-set bone configuration, shadowing may also contribute to the dark color beneath the eyes.