Allison Williams showed off her engagement ring from fiance Ricky Van Veen on Late Night With Seth Meyers, gushing, "I'm obsessed with it." Credit: Peter Kramer/NBC

That girl's got quite the ring! Allison Williams showed off her huge new engagement ring on Late Night With Seth Meyers on Tuesday, March 4. The 25-year-old Girls star's rep confirmed to Us Weekly on Feb. 26 that she's engaged to boyfriend Ricky Van Veen.

"I am obsessed with it," Williams told host Seth Meyers of her ring. "I stare at it a lot."

The actress, daughter of NBC News anchor Brian Williams, has been dating Van Veen, co-founder of College Humor, for three years.

"I was completely surprised," Williams said of the proposal. "The funniest thing about that is I consider myself someone who is impossible to surprise, and yet I am constantly surprised by things. But I walk around the world poised and ready for a surprise."

"And yet a surprise snuck through on you," Meyers said.

"A total surprise and the best kind of surprise," the actress said. "We're really, really thrilled."

How does it feel to be engaged? "It feels a little different. The investment is there," she explained. "It just changes the stakes, clearly. But it's really fun."

One of the biggest changes since her engagement has been her perspective of the reality dating show The Bachelor.

"Suddenly the show feels real!" Williams exclaimed. "I understand the stakes for the first time ever, which is so weird because I have empathy, but for some reason it's never occurred to me, like, 'They're getting engaged on this show!' I was filled with anxiety for the contestants."

Though Williams has already found her man, the HBO star has been a longtime fan of the show -- and recently had her chance to accept a rose.

"They sent me a bouquet of roses on Valentine's Day—the show, not Juan Pablo, not Chris Harrison, unfortunately," she revealed. "The show sent me a dozen roses and said, 'Will you accept these roses?' And I did."