The cushion cut 140 carat diamond, known as The Regent, was discovered in India in 1698. The diamond was acquired by the French Regent, Philippe d’Orléans, in 1717 and has been on display at the Louvre since 1887.
According to the Louvre Museum:
Taking advantage of the economic prosperity that developed in France under the influence of John Law, Philippe d’Orléans, regent from 1715 to 1723, persuaded the Regency Council to purchase the diamond on 6 June 1717. At the time, The Regent outshone all known diamonds in the western world, and by 1719 it had already tripled in value. Today, it is still considered the finest diamond in the world; its color is “of the first water”, that is perfectly white and practically flawless. After the Regency, the gem remained one of the most precious of the Crown’s treasures and adorned all the crowned heads of France.Louvre Museum
The Regent was worn for the first time by Louis XV at the reception of a Turkish embassy in 1721. It was then mounted temporarily on the king’s crown for his coronation ceremony on 25 October 1722. Shortly after his marriage to Maria Leczinska on 5 September 1725, Louis XV began wearing the diamond on his hat, a habit he continued throughout his reign. For the coronation of Louis XVI, on 11 June 1775, a new crown was made similar to that of Louis XV, featuring The Regent on the front. Like his grandfather, Louis XVI sported the gem on his hat. Stolen in 1792, then found again the following year hidden in some roof timbers, the diamond was used as security on several occasions by the Directoire and later the Consulat, before being permanently redeemed by Napoleon Bonaparte in 1801. The First Consul used it to embellish his sword, designed by the goldsmiths Odiot, Boutet and Nitot. In 1812 it appeared on the Emperor’s two-edged sword, the work of Nitot. Following changes in the ruling regime, the diamond was mounted successively on the crowns of Louis XVIII, Charles X and Napoleon III, and finally on the Grecian diadem of Empress Eugénie*.Louvre Museum
The Louvre Museum