Tansen Collection. I cannot find out how this portrait is related to the several sites that mention the Tansen Collection. However, the blog.catherinedelors.com pictures it and describes it as an 18th century portrait of an unknown lady. Catherine Delors has written a charming article about Jane Austen's love of portrait miniatures and the many instances in which they figure in her novels.
Rose Bertin (1747-1813), French Milliner and Dressmaker to Marie Antoinette, she was the first celebrated French fashion designer and is credited with bringing fashion to the forefront of popular culture.