A cluster of roses and rosebuds growing on one thorny stem, all of the purest gold, chiselled with exquisite workmanship. In its cup, among its petals, the Pope, at every benediction he pronounces upon it, inserts a few particles of amber and musk. It is blessed on the fourth Sunday in Lent, and bestowed during the ecclesiastical year on the royal lady whose zeal for the Church has most shown itself by pious deeds or pious intentions. The prince who has best deserved of the Holy See has the blessed sword and cap (lo stocco e il beretto) sent him. If no one merits the gift it is laïd up in the Vatican. In the spring of 1868 the Pope gave the golden rose to Isabella of Spain, in reward of “her faith, justice, and charity,” and to “foretoken the protection of God to his well-beloved daughter, whose high virtues make her a shining light amongst women.” The Empress Eugénie of France also received it.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894