Since the princess first appeared on 29 April wearing the Philip Treacy creation it has become an internet sensation, spawning a dedicated wedding hat Facebook page - 136,900 members and still growing - as well as a photo meme which you can see selections from on the Princess Beatrice and her Hat Tumblr.
Putting the hat's fame to good use, the princess will now auction it off to raise money for charity.
During an interview on The Oprah Winfrey Show Beatrice's mother, Sarah Ferguson, announced: "She's putting it up on eBay to auction it for UNICEF and for Children in Crisis."
Reacting to the news, one Facebook commenter commended Beatrice's decision: "Hats off to Princess Beatrice! [...] It was all in good fun. How wonderful for her to turn it around and make us admire her even more!"
The hat has yet to appear on the auction site but, given the vast number of fans from around the world, we're expecting a bidding war. Add in the fact that even the most modest Philip Treacy design can set you back a few hundred pounds and we advise you start saving immediately!