Hugh Hefner's former fiancee Crystal Harris has put her engagement ring up for auction.

The 25-year-old model broke the Playboy boss' heart earlier this year when she called off their wedding just before the scheduled nuptials in June.

Now she's adding further heartache to the split, by placing the 3.39 carat diamond engagement band under the hammer at Christie's in New York.

According to the listing, auctioneers are expecting the ring to sell for between $20,000 and $30,000.

A source tells Harris "couldn't bear to look at the ring anymore because it brought back bad memories."

The auction will take place in October.