Why Are My Veins Blue and Green?

The appearance of blue is an optical effect due to the wavelengths of the different colors. Our skin reflects more red light than blue and green. This reflection is stronger around the veins, making them appear in a darker hue that our eyes interpret as blue and green veins.
Some people’s veins are more visible beneath their skin. This happens because skin varies in complexion and depth. The thinner and paler the skin, the more visible the veins.
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