Prince Stanisław Poniatowski (November 23, 1754 – February 13, 1833) was a Polish nobleman, politician, diplomat, a member of the wealthy Poniatowski family and a nephew of the last king of Poland, Stanisław II Augustus. He was the official Commander of the Royal Foot Guards regiment directly responsible for the monarch's life as well as the Grand Treasurer of the Grand Duchy of Lithuania (1784–1791) and Governor of Stryj, which made him a key figure in Poland during the Age of Enlightenment. Early life Stanisław was the son of Apolonia Ustrzycka and Polish Prince Kazimierz Poniatowski (1721–1800). His mother, a daughter of Bazyli Ustrzycki, castellan of Przemyśl, was the widow of Prince Antoni Lubomirski. His father was Deputy Chamberlain of Lithuania (1742–1773), Commander of the Royal Army and a knight of the prestigious Order of the White Eagle, awarded on August 3, 1744 in Warsaw. His father was the brother of the last King of Poland and Grand Duke of Lithuania, Stanisław II Augustus, who saw in his nephew a possible successor and heir to the throne of the Polish–Lithuanian Commonwealth. Both Kazimierz and the monarch had been born to Konstancja Czartoryska, (1700–1759), related by marriage to a russophilic Polish–Lithuanian family, the Czartoryskis. Career Poniatowski became a knight of the White Eagle on December 8, 1773. Very well educated and particularly interested in the finances and economy of the country as well as in the arts, Poniatowski was not popular amongst szlachta (the Polish nobility), who found him arrogant and competitive. Poniatowski commissioned about 2500 engraved precious gems from a group of gem-engravers in Rome who turned to classical literature for inspiration. In 1830, Poniatowski published a summary catalogue of his gems, Catalogue des Pierres Gravees Antiques de S.A. le Prince Stanislas Poniatowski, which contained elaborate descriptions. The collection was sold at a Christie's auction in 1839 and has been dispersed ever since. Following the partitions of Poland, Poniatowski emigrated to Italy, living first in Rome, then in Florence. He is the ancestor of the present members of the Poniatowski family bearing the title of Fürst Poniatowski or Principe Poniatowski di Monterotondo. Personal life While some sources state that he married Cassandra Luci (Rome, 1785 - Florence, 1863) in 1806, it is unlikely because she was already married to Vicenzo Venturini Benloch. Together, Cassandra and Stanislaw were the parents of: Isabella Luci (Rome, 1806 - Florence, 1896), married firstly in