A brief genealogical sketch of her is here. A Wikipedia article about her husband is here.
From joaquin-sorolla.blogspot.com/2009/07/retrato-de-la-marquesa-de-balboa; image made lighter by gogm. I checked the Internet extensively to find another image, but even vomprehensice Bastida y Sorolla collection including Cidudad de la pintura, the athenaeum, and Artcyclopedia do not have this portrait.
The marquesa's dress has leg-o-mutton sleeves, dating this to around 1893.
Keywords: Sorolla y Bastida, Felisa de Leon y Navarro de Balboa, de Leon y Navarro de Balboa family, de Borbón y Castellví family, Marquise, Spanish, straight coiffure, tiara, bun, bertha, lace, leg-o-mutton sleeves, necklace, earrings