It wasn't just that Hugh Hefner presented Crystal Harris with an engagement ring on Christmas Eve – it was how he did it that impressed her.

"We were up in the bedroom," Harris, 24, tells PEOPLE, "and my favorite movie is The Little Mermaid, so he had the ring in a Little Mermaid box, and that was so special. I opened it and the first thing he said to me was, 'I hope it fits!' "

Adds Hefner, 84, "I got her a little music box with the Mermaid theme to it, and it just looked like the perfect size and the perfect place to be the ring box. So when she started unwrapping that gift, I reached over and wound it so it was playing music while she discovered what was inside."

Although she cried with happiness, Harris says, "There wasn't any 'down-on-one-knee' or anything like that, because we are not traditional."

The ring is a circle diamond "a little over three karats," says Harris, "and it's on platinum setting and it has diamonds all around the band as well. It's so pretty."

Credit: People

In their first interview since becoming engaged, Playboy founder Hugh Hefner and his gorgeous Playmate fiancee Crystal Harris spoke exclusively to Radar Online about the proposal and revealed that the ring didn’t fit!

"It couldn't have happened in a more loving way," Hef, 84, said about the Christmas Eve proposal.

Crystal said she knew she was getting a ring because one of Hef’s staffers helped her figure out what kind of diamond she wanted, but she was still surprised when he finally presented it to her.

"I love the Little Mermaid and Hef gave me a Little Mermaid music box and he wound it up and when I opened it the ring was in a box inside. I cried!"

"There was no down on one knee; we don’t follow traditions like that. When I opened the box Hef said ‘I hope it fits,’ but it was too big! I had to get it re-sized!"

The happy pair hasn’t set a date yet but Hef told Radar Online that the wedding might become a reality show.

"The wedding will definitely be at the Mansion," Crystal revealed. As for her dress? "I would love to design my own dress."

Hefner told Radar Online that he isn't going to go wild before the wedding, but admitted that he has had a charmed life. "I've been having my bachelor party for the last 50 years."

Crystal said that they have the full support of his children. "I love Hef’s sons, they’re great and they’re really happy about the engagement."

According to Crystal, she and Hef aren’t planning to have any children. "I’ve always said I don’t want kids, just animals and there are plenty around here."

Crystal mused on what she loves most about her new fiancé. "He is the nicest person I’ve ever met in my whole life. He is one of the best influences on me and I love him."

Hef spoke fondly about Crystal. "Her personality and her character are what I love. She's very upbeat and a loving person and doesn't tend to have moods. She is always looking on the bright side. She's not petty, she has good character and is down to earth.

"This is the final act for me and the best," Hef said about his engagement and upcoming marriage to Crystal.

Credit: Radar Online

Hugh Hefner's 24-year-old fiancée Crystal Harris flashed the diamond-laden engagement ring she received when the 84-year-old Playboy founder proposed to her on Christmas Eve.

"For those of you who have been asking to see my ring here it is... My engagement ring from my love @hughhefner," she Tweeted, linking to a picture of the ring.

Harris, December 2009's Playboy Playmate, told News Of The World that between she's "not after Hef for his money" as she has her "own career going."

Hefner's past wives include former Playmate Kimberly Conrad and Mildred Williams.

Credit: Radar Online

Brody Jenner is sandwiched in between his girlfriend Avril Lavigne and step-sister Kim Kardashian during The Kardashians holiday party on Friday, Christmas Eve.

“I’m having 150 people over for dinner,” mama Kris Jenner told USA Today. “So no big deal at all! I’m making all the desserts. I’m working on cheesecake, brownies and a lemon cake for my son-in-law Lamar (Odom). It’s great therapy. We all love to cook. All the girls love to cook. Kim makes a great cupcake.”

“Jesus is the reason for the season!” Kim added. “Merry Christmas twitfam! Love u guys!”

Credit: Just Jared

Stephanie Pratt attends Christmas Eve At The Los Angeles Mission on December 24, 2010 in Los Angeles, California.

Credit: Faded Youth / Wire Image

Vanessa Hudgens and her sister Stella were spotted hiding their faces after working out at a gym in Studio City, CA on December 24, 2010.

Credit: Zimbio

Photos by Photo Agency

Making a preemptive strike against the soon-to-be amassed holiday calories, Kim Kardashian was spotted making her way to the gym for a workout in Beverly Hills, CA on Friday (December 24).

Looking lovely sans makeup, the E! reality star sported a black and white fitness ensemble with her Skecher Shapeups for the Christmas Eve morning sweat session.

Credit: Celebrity Gossip