What is a specific example of irony in Part 2 of Passing?

Clare's Beauty, and Clare's Transgressions (Situational Irony)

By the time Passing reaches its final stages, Irene's discomfort with Clare's passing maneuvers and her distaste for Clare's presence in the Redfield home have become unmistakable. However, Irene still has moments of admiration for Clare. During the tea at the Redfield home, for instance, Irene observes Clare and "couldn't remember ever having seen her look better. She was wearing a superlatively simple cinnamon-brown frock that brought out all of her vivid beauty" (253). Ironically, even as Irene rebels against Clare in virtually every other respect, Irene cannot shake her admiration for Clare's most easy and immediate appeal: her physical beauty.