The condado de Montemar was located in Peru and, according to Wikipedia, the sitter was condesa from 1771 to 1810. She married Fernando Carrillo de Albornoz y Bravo de Lagunas, VI Conde de Montemar, another entity in modern Peru.
From jeannepompadour.tumblr.com/post/136270997819/portrait-of-rosa-de-salazar-y-gabiño-countess-of. Also posted to the Reign of Louis XV - 1715 to 1774 Album here.