Your description of this interesting woman reminded me immediately of this painting that is currently on display at the Frye Museum in Seattle. The artist is someone I've never heard of, a Leopold Schmutzler from Austria, painting around the turn of the century who looks to have been inspired by Sargent.
Speaking of Sargent, check out his many portraits of women with vibrant personalities, on the ARC site. In particular I'm thinking of his portraits of actresses and dancers, but also some of the society women. The portrait of Mrs Hugh Hammersley comes to mind as someone, while traditionally dressed, is posed with an energy and directness.
Sargent's paintings on ARC:
http://www.artrenewal.org/asp/databa...aid=187&page=1