The first English record of the term ‘blue blooded’ to mean noble descent dates to the early 19th century, but the notion actually stretches back much further.
The concept likely originates in medieval Spain as ‘sangre azul’, and is attributed to the rich, powerful families of Castile. As part of their ‘pure Gothic’ descent, they would claim never to have intermarried with another race by drawing attention to their pale skin, which made the blueness of their veins visible.
An English publication of 1811 stated that the nobility of Valencia were divided into three classes – blue blood, red blood and yellow blood – with the first “confined to families who have been made grandees”. In the ninth-century, Spanish military noblemen reportedly proved their pedigree by displaying their visible veins to distinguish themselves from their darker-skinned Moorish enemy.
Throughout Europe it came to express the difference between the upper and lower classes – the former prizing their fashionable marble-like skin complete with visible veins, in contrast to the tanned skin of those toiling in the sun.
Somewhat strangely to our eyes, a gentleman suitor might safely make a compliment to his lady’s turquoise veins, which were also often made prominent in early modern portraits of noblewomen. As a mark of nobility, it was truly desirable. Much like blackened teeth in the Victorian era.