The magnificent appearance of this portrait owes much to the rich red colour of the sitter’s costume. Analysis of a tiny sample suggests that two layers of transparent red lake glaze were used on top of an opaque layer of red pigment to create the intense red of the sitter’s gown. In the lower glaze is a madder lake, while the upper glaze contains high levels of kermes.

The expense and rarity of kermes explains why it is reserved only for the final paint layer. In order to be used for painting, kermes was usually extracted from offcuts of dyed silk. So the same precious pigment could have been used to dye the actual clothes the sitter wears, and to represent those beautifully recreated in his portrait.