This image was provided by Louis Ortiz. Wikipedia identifies it as a Spanish court lady; Louis identifies this as the condesa de Olivares. Her husband is the subject of a flashy Velázquez equestrian portrait. Louis Ortiz provides this (mildly edited) information about the Countess: "Her full name is Doña Inés De Acevedo De Zuñiga y Velasco and she is of the family (probably aunt) of Inés Francisca De Zuñiga y Fonseca, Condesa de Monterrey who appears here.
She was born in Zamora in 1584 and died in Loeches (Madrid) in 1647, belonging to the House of Zuñiga (descendants of the fist King of Navarra Iñigo Arista). She was as Grandee of Spain, Lady-in-waiting of Queen Margaret of Austria (wife of Phillip III), and First Lady of Isabel de Borbón (Elizabeth of France) wife of Phillip IV. She was also tutor of Prince of Asturias Baltazar Carlos.
Doña Inés was subject of Spanish writer Benito Pérez Galdós in his book Doña Perfecta, portraying her as a perfect example of the tipical Spanish woman just as beautiful, perfect and admirable like a rose and its thorns."