Beckendorff is a German name, but a New York Times article shows the Baroness' husband was serving the Russians. She was born Gertrude Orr of Kentucky.
From the USA Library of Congress Bain collection; a flaw in the lower skirt and spots in the skirt were fixed with Photoshop by gogm.
The Baroness appears to be wearing a leather over-bodice and skirt.
Keywords: straight coiffure, under-bodice, long full sleeves, cuffs, scoop neckline, vest over-bodice, lapels, square neckline, natural waistline, tight skirt, floral bodice ornament, necklace, bracelets