During the Renaissance the color of red was achieved in painting with the use of vermilion.
“Vermilion was made from cinnabar, a brick-red mineral the ancient Romans believed came from the blood of dragons crushed to death under the weight of elephants.”**
So silly and yet so specific!
**King, Ross (2012-10-30). Leonardo and the Last Supper (p. 149). Bloomsbury Publishing. Kindle Edition.