$5000 for slice of Diana's wedding cake

A woman holds a piece of wedding cake from the wedding of Prince Charles and Princess Diana in 1981. Photo / Getty

A slice of Princess Diana's and Prince Charles' wedding cake is set to sell for a staggering US$4000 ($5780) at auction in Los Angeles.

The 34-year-old fruit loaf has been preserved in an ornamental doily in a box since the wedding at Buckingham palace in 1981.

And it's been perfectly preserved thanks to the high quantity of alcohol in the recipe, making it still edible three decades on.

Accompanying the cake is a note that reads: "With best wishes from Their Royal Highnesses, The Prince & Princess of Wales."

Diana and Charles on their wedding day, July 29, 1981. Photo / Getty

Sam Heller, from the LA auction house, Nate D. Sanders told the Daily Mail: "The wedding of Lady Diana and Prince Charles captured the attention of the world on television and through many newspapers and magazines.

"And even today, people just can not get enough of the late Princess."

He noted while the cake is still edible, collectors will likely keep it intact.

"Collectors are willing to pay a premium to own a piece of history from the most famous wedding of the 20th century."

- nzherald.co.nz