A canonical coronation is a pious institutional act of the Pope, duly expressed in a Papal Bull, in which he bestows an ornamental crown, diadem, or halo to a Marian, Christological, or Josephian image or statue that is widely venerated in a particular diocese or locality.
The formal act is generally carried out by a representing proxy of the Pope, a Papal legate, or on rare occasions by the Pontiff himself, by ceremonially attaching a crown, tiara, or stellar halo to the devotional image or statue.
Originally, the Holy Office issued the authorization of a canonical coronation through a dicastery, called the “Vatican Chapter”. Subsequently, until 1989, the Vatican’s Sacred Congregation of Rites was assigned this duty. Since then, the Congregation for Divine Worship and the Discipline of the Sacraments arrange to execute the ceremonial act which the decree authorizes.