According to her Wikipedia article, Zofia Potocka led a spectacular life, rising from almost slavery to a noble's wife. The lead paragraph states, "Zofia Konstantinova Potocka, née Clavone (12 January 1760 — 24 November 1822) was a Greek prostitute, slave, spy and eventually a Polish noble as the spouse of Stanisław Szczęsny Potocki. She was famous in contemporary Europe for her dramatic life and her love affairs and known as the lover of Grigory Potemkin."
The original caption for this portrait is "PFA188032 Portrait of a Young Lady (pastel on paper) by French School, (18th century) pastel on paper 61x48 Private Collection © Bonhams, London, UK French, out of copyright." The reliable batguano site has this, "Countess Zofia Constantinova Potocka (1766-1822). Formerly in the Berlin Museum; probably destroyed by bombs in WW II. This pastel copy was sold at Bonhams in London as the work of Kucharski..." A brief biographical sketch then follows.