Boston Celtics forward Kris Humphries is planning to auction off the massive engagement ring he gave Kim Kardashian prior to their now infamous 72-days of marriage.

According to Yahoo, the 20-carat Lorraine Schwartz diamond ring, featuring a 16.21-carat center stone and two 1.80-carat stones on the side, is on the docket for an upcoming Oct. 15 sale at Christie's auction house in New York.

While Christie's has refrained from identifying Humphries by name, they describe the seller as a "gentlemen." A source told Yahoo, Kardashian, who recently had a baby with hip hop boyfriend Kanye West, always knew this day would come.

"Kim has been waiting for the day he would auction it," the source told Yahoo. "Everyone always asked what Kim did with the ring---she silently gave it back over a year ago. And Kris waited until the divorce was final to sell it."

Christie's estimates that the ring will fetch anywhere between $300,000 and $500,000 at auction. Yahoo reports Humphries paid in the neighborhood of $2 million for the ring when he purchased it and proposed to Kardashian in 2011.

Humphries, 28, was dealt to Boston this off season as part of multi-player deal that shipped longtime Celtics veterans Paul Pierce and Kevin Garnett to the Brooklyn Nets. In 65 games for the Nets last season, Humphries averaged 6 points and 6 rebounds.