Why does Mary wear blue?
This is a medieval artistic invention. Mary has always had a special place in the Roman Catholic belief, and so when showing her in art, it was decided that she should somehow be ‘special’. In those days, most paint pigments were made from substances found in the earth (they had no artificial dyes as such) so that yellow and brown wre made from types of earth called ochres, black was made from powdered charcoal, and red and white from lead oxides found in the earth. However, there was no cheap source of blue. The only source of blue pigment was the precious stone ultramarine which was more expensive to buy than gold leaf. So, frequently in religious paintings, the painting was done solely by using the cheap ocres and oxides easily obtained from the ground, but the only blue would be that worn by the Virgin Mary to make her stand out as someone very special indeed.
