From the collection of Grand Duchess Maria Pavlovna of Russia (1786-1859), grandaughter of Catherine the Great and wife of the Grand Duke of Saxe-Weimer-Eisenach.

https://en.wikipedia.org/wiki/Grand_Duchess_Maria_Pavlovna_of_Russia_(1786%E2%80%931859)#:~:text=Grand%20Duchess%20Maria%20Pavlovna%20of%20Russia%20(Russian%3A%20%D0%9C%D0%B0%D1%80%D0%B8%D1%8F%20%D0%9F%D0%B0%D0%B2%D0%BB%D0%BE%D0%B2%D0%BD%D0%B0%3B,of%20Saxe%2DWeimar%2DEisenach.

https://www.kollerauktionen.ch/en/317976-0005-----1171-SMARAGD-DIAMANT-BROSCHE_-Russ-1171_56891.html