A piece of cake from Princess Diana and Prince Charles' 1981 wedding will be up for auction.

The slice is estimated to go for up to $350, according to Dominic Winter Auctioneers.

The wedding cake slice has a coat-of-arms design colored in red, silver, gold and blue. It also features a small silver horseshoe and leaf spray with white decorative icing. (Dominic Winter Auctioneers via AP) (Dominic Winter Auctioneers via AP)

The piece weighs in at about 28 ounces and was cut out of the 23 cakes made for the July 29, 1981 wedding, Dominic Winter Auctioneers wrote on its website. The wedding cake slice has a coat-of-arms design colored in red, silver, gold and blue. It also features a small silver horseshoe and leaf spray with white decorative icing.

A piece of cake from Princess Diana and Prince Charles' 1981 wedding will be up for auction estimated to go for up to $350, according to Dominic Winter Auctioneers. (Photo by Terry Fincher/Princess Diana Archive/Getty Images) (Terry Fincher/Princess Diana Archive/Getty Images)

The cake slice was given to Moyra Smith, an employee to the Queen Mother at Clearance House, according to the auction house’s description. This Royal Wedding slice of 40-year-old cake icing was acquired by Dominic Winter Auctioneers in 2008.

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"It appears to be in exactly the same good condition as when originally sold, but we advise against eating it," a description for the slice reads.

The Royal Wedding cake slice also includes a printed Ceremonial and Order of Service program for the wedding in St Paul's Cathedral, and a memorial Royal Wedding Breakfast program for Buckingham Palace, the listing says.

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The auction will start on August 11 with the lowest starting bid expected to go for $278.

Slice of Princess Diana's, Prince Charles' royal wedding cake to be auctioned off

The 40-year-old cake slice is estimated to go for up to $350