Thus Saint Catherine recounts the apparition in which the Virgin entrusted her with having the Medal struck: on November 27, 1830, at 5:30 p.m., «I seemed to hear a noise like the rustling of a silk dress. I raised my head and, looking in that direction, saw the Most Holy Virgin. She was of medium height and so beautiful that it is impossible for me to describe her». The Queen of Heaven appeared to her standing on a globe entwined by a greenish snake mottled with yellow, holding between her hands, raised to chest height, another, smaller globe, which she offered to God in a supplicating gesture.
Suddenly, her fingers became covered with rings adorned with precious stones, which emitted beams of light with a thousand reflections. These encircled the Blessed Virgin with such splendor that her feet could no longer be seen. While Sister Catherine was completely absorbed in the marvelous vision, the Most Holy Virgin lowered her eyes toward her and said: «The small globe you see represents the entire world and each person in particular. The rays from the rings symbolize the graces that I pour out on those who ask me for them». Suddenly, the beautiful figure of the Blessed Virgin appeared framed in its upper part by an oval formed by the following words, written in letters of gold: «O Mary, conceived without sin, pray for us who have recourse to you!». Then Mary's hands, laden with graces symbolized by the rays, lowered and extended, assuming the graceful, maternal pose reproduced on the Medal.
Suddenly, the image turned around, and the nun saw the reverse of the Medal. It bore the letter “M” (the initial of the name Mary), surmounted by a cross resting on the letter “I” (the initial of the name Iesus, Jesus). Below were two hearts: one surrounded by thorns (that of Jesus), the other pierced by a sword (that of Mary). Finally, twelve stars surrounded the whole. Our Lady said to her: «Have a Medal struck according to this design; those who wear it will receive great graces, especially if they wear it around their neck; graces will abound for those who wear it with confidence».

The Conversion of Alfonso Ratisbonne

Two years later, the Medal was minted with the approval of the Archbishop of Paris, and from then on it spread rapidly throughout the world. Through it, countless graces of healing and conversion were obtained, including the famous conversion of Alfonso Ratisbonne, which led it to be called the “Miraculous Medal.”
Alfonso Ratisbonne was a young Jewish man, an atheist, and a detractor of the Christian religion who was suddenly struck by the beauty of a vision of Mary in the Roman church of Sant'Andrea delle Fratte. He had entered there by chance while waiting for a friend, who a few days earlier had managed to persuade him to wear the Medal around his neck before undertaking a major journey. Meanwhile, the friend, together with other Catholic friends, was praying fervently for his conversion. That conversion later became the subject of a personal, public, and detailed “confession,” which caused unanimous emotion in 1842. Alfonso Ratisbonne was baptized and went on to become a Christian apostle, working in his homeland, in Jerusalem. In Rome, in the “Chapel of the Miracle” of the Basilica of Sant'Andrea delle Fratte, where the Jewish man Alfonso Ratisbonne converted, these words can be read beside the large painting depicting the apparition: «On January 20, 1842, Alfonso Ratisbonne of Strasbourg came here as a stubborn Jew. The Virgin appeared to him just as you see her. He knelt down a Jew and rose as a Christian. Stranger, carry with you this precious reminder of God's mercy and the power of the Virgin.»