The Irish crown jewels were stolen in 1907. To this day, no one knows who absconded with the regalia. While known as the “Irish crown jewels” today, they were not referred to as such until after their theft. In fact, they were the regalia of the Order of St. Patrick, a British Knightly Order associated with Ireland (England and Scotland had the Order of the Garter and the Order of the Thistle, respectively) and were worn by either the British monarch or their stand-in during investiture ceremonies or other state events.
When they were stolen in 1907 from a safe in Dublin Castle, there was no sign of a break in, no forced locks, an no other damage of any kind. Since 1907 theories about the theft of the crown jewels have ranged from an operation carried out either by Irish Unionists or British Republicans to humiliate the monarchy, blackmail and bacchanals at Dublin Castle, jewel stealing femme fatales, and simple drunken incompetence. To this day, the fate of the jewels remains an enduring mystery.