The Miraculous Medal is based on an apparition of Our Lady of Grace to Sister Catherine Laboure. It contains an image of Mary with rays of graces extending from her hands with the words “O Mary, conceived without sin, pray for us who have recourse to thee.” On the back is a ring of twelve stars, the letter M surmounted by a cross, and two hearts---the Sacred Heart of Jesus and the Immaculate Heart of Mary.