Portrait of an unknown in a blue caftan Fedor Rokotov (1735-1808)

The picture has something of this: people, portrait, wear, man, necklace, jacket, leader, writer, woman, elderly, brunette, scientist, poetry, engraving, royalty.
Perhaps it’s a close up of a painting of a person wearing a blue coat and a white shirt with a black bow around his neck and a smile on his face.