Sadly I don't think the portrait is of Lucy. I have searched online and it's a Portrait of Countess Ferdinand Colloredo-Mannsfeld 1913) by Philip Alexius de László (1869-1937), an English painter, Oil on canvas. https://commons.wikimedia.org/wiki/File:Laszlo_-_Countess_Ferdinand_Colloredo-Mannsfeld.jpg
Her maiden name was Eleonore Iselin (New York 27 Dec 1881-New York 25 Feb 1939) and she married Ferdinand Johannes Hieronymus Maria Colloredo-Mannsfeld (Sierndorf 5 Jun 1878-Vienna 18 Dec 1967) in New York on 10 May 1909. Ferdinand was from another branch of the noble Austrian Family to Lucy's fella, Joseph II, who married again but had no children. The Colloredo-Mannsfeld family had a tough time of it with the Nazi annexation of Austria, followed by the Soviets nationalising the family's properties in Czechoslovakia, so maybe Lucy was better off with Rupert after all, even though he was a bit of a cad...
I am conscious that I am probably misusing GMIC as I am searching for information on Lucy Jonquet, but if anyone (dante?) can put me on the right track, I'd be interested to hear...
Thanks, it's been fun.