Probably Penelope Devereux, daughter of Lettice Knollys, great-granddaughter of Mary Boleyn
From lisby1's photostream on flickr.
Penelope Devereux (?) wears her hair frizzy and a deeply goffered neck ruff and clip-on style sleeves in this miniature portrait. Her dress has a bertha, but both ruff and bertha are of plain material.
Keywords: Hilliard, Penelope Rich, Devereux family, Rich family, frizzy coiffure, jeweled feathered headdress, veil, round neckline, neck ruff, crescent neckline, bertha, full sleeves, necklace, draped necklace, earrings, brooch, jeweled bodice