I cannot find anything about her.
From bbc.co; lower part of left edge and vertical flaw in left center of the background were fixed with Photoshop.
Lady Gertrude's open neckline area eases the impact of her wide lace collar. Her pearl jewelry adds to the impact of her black dress.
Keywords: 1630, van Ceulen, Gertrude Howard, Howard family, curly coiffure, hair jewelry, trapezoidal neckline, lace collar, full paned virago sleeves, jeweled arm bands, girdle, vee waistline, necklace, earrings, brooch