You may enjoy this. In researching for my book I ran across this in the autobiography of Lady Diana Manners, aka Diana Cooper. She was at Oxford with Felix. "But the most eligible of all was Prince Felix Youssupoff.... A mystic, and of transcendent beauty, he sang to his guitar the Russian gypsy songs,...At the fancy balls he wore his eighteenth-century Russian dress of gold and pearls and sables and aigrettes, with embroidered boots and jewelled scimitar." I am told by a friend, that the famous Tatar costume in which he was photographed, is in Mexico and may be brought to the US for restoration (for what purpose I don't know!).