Author J.K. Rowling signs copies of her seventh and final Harry Potter book, "Harry Potter and the Deathly Hallows", during an open book tour stop at the Kodak Theater in Los Angeles October 15, 2007.
Author J.K. Rowling signs copies of her seventh and final Harry Potter book, "Harry Potter and the Deathly Hallows", during an open book tour stop at the Kodak Theater in Los Angeles October 15, 2007. Reuters/Chris Pizzello

A first edition of “Harry Potter and the Philosopher’s Stone” books can fetch owners as much as £ 20,000 (AU$33,800) if their copy has a certain typo. The error exists in just 500 hardback copies of JK Rowling’s first “Harry Potter” novel.

As first reported by the Independent, 500 hardback copies of the first edition of the “Philosopher’s Stone” have an inconspicuous error. The words “1 wand” are repeated twice in Harry’s list of supplies for first-year wizards going to Hogwarts. The passage appears on page 53.

A copy with the error is estimated to cost 15,000 to £ 20,000 (AU$25,400 to AU$33,800) at the Bonhams Fine Books and Manuscripts Sale in London on Nov. 9. The copy is said to be in exceptionally fine condition.

“As the first book in the series, ‘Harry Potter and the Philosopher’s Stone’ has a special place in the affections of the millions of readers across the world and the proof reading error about the wand in the first edition has, of course, become a treasured piece of Harry Potter arcana,” Matthew Hale, Bonhams Head of Books and Manuscripts, said in a statement.

“Like most enduring books aimed at younger readers, the Harry Potter books also have wide appeal to adults and there is a strong market among collectors for first editions. This copy is in excellent condition – one of the very best I’ve seen – and we’re expecting a lot of interest.”

The auction house has not released other items included in the sale yet.

The first “Harry Potter” book was published in 1997 by Bloomsbury. Although the first edition comes in various formats, the most valuable is the first impression of the hardback, which carries the number sequence 10 9 8 7 6 5 4 3 2 1 on the reverse of the title page. According to Bonhams, the second impression of the hardback also has some value, as is the first impression of the paperback.