Mary-Kate Olsen [1]'s massive diamond sparkler [2] has been making the rounds across multiple countries [3] since her engagement to Olivier Sarkozy [4] late last month, but we haven't seen the couple together until now. They stayed close at a Diane von Furstenberg-hosted release party for author Bob Colacello's new book on Monday in NYC, both wearing black ensembles; in fact, they wore very similar-looking lace-up dress shoes to the bash as well. During the party, Mary-Kate stopped to chat with the author as he signed a copy of his book, Holy Terror: Andy Warhol Close Up, for her as she showed off her ring.

Though Mary-Kate and Olivier haven't spoken out about their wedding plans yet, they may be planning another big step in their relationship — a baby. The couple is reportedly already trying to get pregnant [5], in spite of Mary-Kate rejecting Olivier's first proposal a year ago so that they "didn't move too fast."