Crystal Harris, Hugh Hefner's 25-year-old ex, is putting the engagement ring she received from the Playboy mogul up for auction, according to E! News.

The ring - a 3.39-caret diamond rock which Hef bought for $90,000 - is going to be auctioned at Christie's.

It is expected to sell for somewhere between $20,000 and $30,000.

In December 2010 Harris and Hefner got engaged. But she broke off the engagement five days before their wedding, in June 2011.

To add insult to injury, Harris then went on to tell Howard Stern about their private moments.

She revealed that she and Hefner had only been intimate once in over two years. And her review was less than stellar.

Harris is the second Hefner-ex to be in the headlines this week.

Holly Madison's name has been circulating these days after the former Playmate insured her breasts for $1 million with Lloyd's of London, a British based insurance and reinsurance market.