The “Miraculous” Medal was made according to Our Lady’s design

Saint Catherine Labouré (1806 - 1876), a Daughter of Charity residing at the Motherhouse of the Congregation, 120 Rue du Bac in Paris, received apparitions of the Virgin Mary in July, November and December 1830, during her novitiate, in the chapel of her convent. These apparitions are at the origin of the Miraculous Medal, which was freely circulated and in a short time was worn by millions.
It is still worn today by many Catholics.
Catherine was beatified in 1933 and canonized in 1947 by Pius XII.
Here is an excerpt from her testimony on the apparitions, given to her spiritual director in 1830:

"Catherine also heard an interior Voice telling her, ‘These rays are symbols of the graces that Mary obtains for men.’ Around the painting that depicted her vision was inscribed in gold letters, ‘O Mary, conceived without sin, pray for us who have recourse to you.’ Catherine added that she had heard, ‘I pour out these graces on whoever asks for them.’ She made me understand how pleasant it was to pray to the Blessed Virgin and how generous she was to those who prayed to her; how many graces she granted to those who asked her, and what joy she experienced in granting them.

A few moments later, the painting seemed to rotate, showing a circle of twelve stars, a large letter M surmounted by a cross, and the stylized Sacred Heart of Jesus and Immaculate Heart of Mary underneath. After Catherine had carefully considered all this, the voice said to her, ‘Have a medal made according to this model. All who wear it will receive great graces and will enjoy special protection from the Mother of God.’"

The Marie de Nazareth team