https://www.sensationalcolor.com/blue-blood/

Aristocrats were originally the only ones who could afford medicine, often in the form of colloidal silver (the liquid into which silver particles are suspended and was thought of as a cure-all for many different illnesses); could have a considerable number of silver coins and could have worn silver jewelry; and could have eaten off silver plates and used real silver cups and tableware which were later found to shed nano silver particles under a microscope. Hence, argyria was common only to those who were born with a silver spoon in their mouths.

Historians suspect that argyria could have been the origin of the term “blue blood” is used to describe people of noble birth. In earlier times, it was common for European nobillity to have skin that appeared to have a blue or greenish cast especially made obviou...