The Regent diamond was a diamond that was a whopping 410 carats uncut. It was found by a slave in the Kollur mine in India. The slave smuggled it out of the mine: Some say in his rectum and others claim it was placed in a large wound in his leg. Then an English sea captain killed the slave, stole the diamond, and sold it to a merchant in India.
An English merchant named Thomas Pitt bought the diamond from the merchant while in Madras in 1701. Because of Pitt’s ownership, the diamond became known as the Pitt diamond because he cut the diamond into a 141 carat cushion brilliant that was described as “almost round in shape, of a thickness equal to its width, perfectly white, free from all blemish, cloud, or speck of admirable water.”
He then attempted to sell the diamond to various European royals, including Louis XIV without success. Eventually, however, it was purchased by Louis XV’s Regent, Philippe II, Duke of ‘Orléans in 1717. The duke was encouraged to purchase it by his friend, the famed memoirist, Louis de Rouvroy, Duke of Saint-Simon.
The Duke of Orléans had the diamond set into the crown used at Louis XV’s coronation in 1722. At that time it became known as the Regent diamond. Later, when Louis XVI was crowned, the monstrous diamond was set into his new crown, and when the new king wore it, he reputedly cried out in discomfort, “It hurts me!”
To safeguard the Regent diamond and France’s crown jewels during the French Revolution, all the jewels were stored at the Garde-meuble (Royal Treasury). Despite this safeguard, the Regent diamond and other crown jewels were stolen by rioters who broke into to the Garde-meuble. The thieves were aided “by the help of the rough masonry and the ropes of a lantern.” Two of the thieves were caught and some of the jewels recovered. However, the Regent diamond remained missing and was not discovered for fifteen months because robbers had hidden it in a hole, “an inch and half [in] diameter in the timber-work of a garret [in a building in Paris].” One person remarked:
“The two thieves then in custody upon being question gave, of course, answers which aroused … suspicions … It seemed certain … that the robbery had been planned by persons belonging to the late dominant aristocratic party in order to supply themselves with money to be used in paying the foreign troops who were to subdue France … [However,] it seem … that none except the thieves themselves were concerned in this astonishing robbery and that they were actuated by greed alone. The patriots only made use of it for party purposes to obtain their own objects, just as they tried to utilize in the same way any uncommon natural phenomenon, such as comets, earthquakes, or hail stones.
After the Regent diamond was recovered it was used to secure loans for bankrupt France: In 1795, it was pledged to German banks, and in 1798 it was pawned to a banker of Amsterdam named Vandenberg. While in his possession, he placed it in a glass case for public exhibition. Vandenberg’s friends thought him crazy because of the lack of security and advised him that it could be easily stolen. However, he told them “with a tinkling eye, ‘The Regent that is in the glass case is worthless … the real Regent is in my wife’s stays.'”
Napoleon Bonaparte permanently redeemed the Regent diamond in 1801. At his coronation in 1804, instead of mounting it into his crown, he had it mounted into the pommel of his sword situated “between the teeth of a crocodile, forming the handle of sword.” It next appeared when Napoleon wedded the Archduchess Marie Louise of Austria. His black velvet bridegroom cap was “adorned with eight rows of diamonds and three white plumes fastened by a knot with the Regent blazing in the centre of it.”
After Napoleon was exiled, the Archduchess Marie Louise of Austria, fled. She took all of the crown jewels, including the Regent diamond, to Austria. It remained there until her father returned it to France. Three of France’s rulers — Louis XVIII, Charles X, and Napoleon III — then mounted into their crowns.
Of the diamond’s value, The North British Review commented:
“According to one statement, it was valued in 1791, by a commission of jewellers, at twelve millions of livres; and according to a  MS. now before us at, £458,333, which nearly the amount of twelve million of livres.”
In 1877, all of France’s crown jewels, except for the Regent diamond, were sold at auction. The Regent diamond, which had been mounted into a Grecian diadem designed for Empress Eugenie, was instead put on display at the Louvre. Since that time the Regent diamond has remained on display at the Louvre except for a short period during World War II when it was hidden behind a stone panel at the Château du Chambord as a protective measure.
-  Saint-Simon, Louis de Rouvroy duc de, Memoirs of the Duc de Saint-Simon on the Times of Louis XIV, and the Regency, Volume 4, 1899, p. 109.
-  Lippincott’s Monthly Magazine, Volume 56, 1895, p. 376.
-  Ibid.
-  Wide Awake, Volume 28, 1889, p. 17.
-  Lippincott’s Monthly Magazine, p. 377.
-  Ibid., p. 373-374.
-  Wide Awake, p. 19.
-  The North British Review, 1853, p. 215-216.