> Veins close to the surface of the skin appear blue for a variety of reasons. The factors that contribute to this alteration of color perception are related to the light-scattering properties of the skin and the processing of visual input by the visual cortex, rather than the actual colour of the venous blood which is dark red.[6]
I get what you mean, but this is also like saying a butterfly doesn't have color.
The blue in blue eyes (and green) is a structural property, not a pigment property. This is also why eye color changes for these people much more dramatically than people with darker colored eyes (see Hazel eyes).
It's color caused by structure, but that doesn't make it not a color. A lot of things aren't going to "have color" if you use that definition. Including the sky...
Human blood can turn blue when consuming enough (collodial) silver?
Like when rich people consumed food and beverages from pure silver plates (100's of years ago) their blood supposedly turned purple/blueish. Hence the term (at least in Dutch) that "he is of blue blood" = he rich af.
Perhaps, but according to etymonline the term comes from Spain, where certain families described themselves as having "blue blood" to emphasize that they had no Moorish ancestry. The contrast being drawn isn't one between nobles and laborers. It's between indigenous nobles and intrusive nobles.
