"Certificate Prof. Dr. Helmut Börsch-Supan, Berlin, 18.9.2022 Sophie Karoline Marie (1737-1817) was a daughter of Duke Charles I of Brunswick-Wolfenbüttel and a younger sister of Anna Amalia of Weimar. In 1758 she married Margrave Friedrich III of Brandenburg-Bayreuth, who before had been married in his first marriage to Wilhelmine of Prussia, a sister of Frederick the Great. Her husband died after only three years of marriage and Sophie Karoline Marie moved to Erlangen, where she had her widow's seat for 53 years as the "Erlanger Markgräfin". Prof. Helmut Börsch-Supan attributes this portrait to Barbara Rosina Lisiewska-de Gasc, a daughter of the Prussian court painter Georg Lisiewski, who taught her painting along with her siblings Anna Dorothea and Christoph Friedrich. Barbara Rosina Lisiewska was first married to the painter David Matthieu, after his death to Ludwig de Gasc, court assessor in Berlin and professor of French literature in Braunschweig. Prof. Börsch-Supan succeeded in identifying the sitter on the basis of a portrait of Sophie Karoline Marie by Johann Georg Ziesenis (cf. Karin Schrader: Der Bildnismaler Johann Georg Ziesenis (1716-1776), Münster 1995, no. 158, with two workshop replicas no. 158a and 158b), which was formerly housed in Blankenburg Palace and was sold at Sotheby's major auction in Marienburg Palace in 2005. According to this, the present painting, which Prof. Börsch-Supan dates to the time shortly before the marriage of the Brunswick princess to the Bayreuth margrave in 1759 or at the latest before his death in 1763, was the model for the portrait by the Hanoverian court painter Ziesenis."