The piece of fruitcake, housed in a special box marked on the cover, "CD, Buckingham Palace, 29th July 1981," is expected to fetch USD 800.
It includes the original presentation card, "With best wishes from, Their Royal Highnesses, The Prince & Princess of Wales."
Accompanied by the original mailing package, with label issued to "Mrs J L Faulkner."
The cake was created and baked by David Avery, the head baker at the Royal Naval cooking school for the wedding that took place on July 29, 1981, according to the RR auctions.
Among them is Princess Diana's jewelled evening bag that is expected to sell for USD 12,000. Bidding for the items will close on December 6.