Our Lady is nearly always depicted in art as wearing the color blue. We wondered why, and a quick search of the internet turned up an Aleteia article which addressed this issue.
Here’s an excerpt from that article:
For the people of Israel blue brings to mind the following of God’s Commandments, as opposed to a person’s selfish will.
This was perfectly lived out by the Blessed Mother who said, “Behold, I am the handmaid of the Lord; let it be to me according to your word” (Luke 1:38). She was the faithful “Daughter of Zion” who fulfilled the call of obedience that God had asked of the Israelites.
Additionally, Numbers indicated that “the Levites are to ‘spread over [the Ark of the Covenant] a cloth all of blue’ (4:6). And further: ‘And over the table of the bread of the Presence they shall spread a cloth of blue’ (4:7).”
Mary is traditionally referred to as the new Ark of the Covenant, as she held within herself the Divine Presence of God.
On the other hand, the Byzantine/Orthodox tradition of clothing Mary in blue has a different meaning.
Blue in iconography represents transcendence, mystery, and the divine. It is the color of the sky and as a result is viewed as a heavenly color.
Red in contrast is seen as an earthly color, the color of blood.
Jesus is typically depicted in icons with a blue outer garment and a red inner garment, symbolizing how divinity wraps his humanity.
Mary on the other hand is seen with a red outer garment and a blue inner garment, representing how she carried divinity (Jesus) within her humanity.
…blue is a very important color in the artistic traditions of Christianity and has deep spiritual meanings that bring out different attributes of the Blessed Mother. It is a sacred color, one that reminds us of Mary’s faithfulness and her privileged role in salvation history.
Here is a link to the full article: https://aleteia.org/2017/06/24/why-is-the-blessed-virgin-mary-always-wearing-blue/