The words and pictures engraved on the medal represent three closely tied messages.
Oh Mary, conceived without sin, pray for us who have recourse to thee.
The identity of Mary is explicitly revealed to us here: the Virgin Mary is immaculate from the moment of her conception. This privilege is already bestowed upon her through the merits of the Passion of Jesus Christ, and from it flows the all-powerful nature of her intercession for those who pray to her. This is why the Virgin invites all to have recourse to her in the difficulties of life.
Her feet are planted on a half-ball, and they are crushing the head of a serpent.
The half-ball is a half-globe, the world. The snake, for Jews and Christians, personifies Satan and the forces of evil. The Virgin Mary is herself engaged in a spiritual battle, the battle against evil, of which our world is the battlefield. She calls us also to follow God’s way, which is not the way of the world. It is this true grace resulting from one’s conversion that the Christian must ask of Mary to bring it to the whole world.
Her hands are open and her fingers are adorned with rings, decorated with precious stones. Rays of light are emitted from these jewels, becoming increasingly bigger as they are beamed toward earth.
The radiance of these beams, like the beauty of the apparition described by Catherine, reaffirms our trust in the faithfulness of Mary (the rings) towards her Creator and towards her children, in her intervention (the rays of grace being beamed to earth), and in final victory (the light itself), since she, as the first disciple, is the first saved.