Things between Mary-Kate Olsen and her boyfriend Olivier Sarkozy might be getting super-serious, as the fashionista was seen "checking out huge engagement rings at the Neil Lane store" in Los Angeles multiple times last month, Breaking Celebrity News has learned.

"She really likes cushion-cut diamonds, and all of the rings she has looked at are over five carats," an insider told the NY Post. "She has narrowed it down, but still hasn't made a final decision."