According to legend, the Regent diamond ( 140,6 carats ) was discovered by a slave in a diamond mine in 1692 in India. He stole the diamond and hid it in a wound inside of his body.
The slave was killed on a ship and the captain took the diamond. It was sold to Thomas Pitt a well known merchant trader in India. He finally managed to sell it to Philippe II, Duke of Orleans in 1717.
It was set in a Crown for the Coronation crown for Louis XV and then in another crown for Louis XVI in 1775. He gave it to Marie Antoinette who added it to her jewelry collection.
The diamond was, stolen, hidden, and eventually recovered. It then found its way into the hands of Napoleon Bonaparte in 1801. It was set into his sword until his death when it was sent to Austria. It was eventually returned to France and was set into the crowns of Louis XVIII, Charles X and Napoleon III.
The diamond was then set in a Greek style Diadem crown for Empress Eugenie where it remains today… It is displayed in the Louvre Museum.