Why are members of the royal family said to have 'blue blood'?

It wasn't just royals that were referred to as having blue blood - it was the aristrocracy and it was becuase they didn't expose themselves to the sun and weren't doing jobs where their hands could get dirty, therefore the veins were easier to see and, as veins look blue they were referred to as having blue blood.

Why are members of the royal family said to have 'blue blood'?
It might be the first answer but I think it also has something to do with haemophilia which is a disease often associated with male royalty. It means that the blood doesn't clot and, therefore may appear more blue than red.
Reply:I believe I read once that it is to do with the pale skin of aristocrats in comparison to the working man - because of that pale skin the veins stood out much more clearly, looking very blue.
Reply:because they are different from other people they must be treated like royalty that's why!
Reply:It's a term used to specify that royals are different from others.
Reply:because their blood is blue!