One of the most common colours used in statuary and iconography for the Blessed Virgin Mary is blue. With a quick image search online, nearly every image that pops up has Our Lady wearing something blue. It’s so common that many Catholics take it for granted. The colour blue has enough general associations that we can apply to Mary: it is the colour of the sky/the heavens, and represents peace and tranquility. Tranquility befits Our Mother, who kept all the events of her Son’s life in her heart (cf. Luke 2:19, 51). Use of the colour blue for the Virgin Mary goes beyond those basic associations. It has its roots in the Old Testament, Church history, and her apparitions throughout the last several centuries.