The penny is the lowest mintage pre-decimal Australian coin in existence - a "numismatic superstar" with its value only rising, according to Lloyds Auctions chief operations officer Lee Hames.

The highly collectable coin is in good condition and features a partial diamond and six pearls on King George V's crown.

Bidding for the penny stood at $14,000 as of Friday morning but auctioneers expected it to break records and fetch more than $40,000.

Pennies in average condition normally sell for between $15,000 and $20,000.

"It is extremely rare to see such an authentic Australian penny go to auction. This is someone's chance to own one of the rarest coins in the country," Mr Hames said.

"A once by-product of economic depression is now a symbol of prosperity, the ultimate cherry on top for any coin collector."

In 1929, at the start of the Great Depression, deflation and Australia's shrinking economy meant a lower demand for currency and the government did not order any pennies to be minted.

An accidental minting of the 1930 penny meant 3000 were produced - but only about 1500 ended up in circulation, with many of the coins damaged or discarded.

It is unclear how many remain in collectors' hands, according to Lloyds.

The penny will go to auction on Sunday night, along with other collectable coins.

Australian Associated Press