The Lorraine Schwartz dazzler, which features a 16.21-carat centre diamond and two 1.8-carat side diamonds, was sold at Christie's in New York on Tuesday.
Bidding began at $200,000 in the 'Bright and Beautiful' auction and the anonymous online buyer sealed the deal at around a third of the band's reported value.
The ring was estimated to fetch between approximately £190,000 and £320,000.
Last month it was revealed that basketball player Kris would sell the ring with which he proposed to reality TV star Kim in the auction and that a portion of the proceeds would go to charity.
Kris and Kim were married for 72 days in 2011 before the new mum filed for divorce.The Keeping Up With The Kardashians star was pregnant with her boyfriend Kanye West's child at the time that the divorce was settled.
Kim, who gave birth to the couple's adorable daughter North West in June, lost the engagement ring to her husband in the settlement after an 18-month battle.
At the time, the NBA player sought an annulment of their marriage, claiming it was based on fraud and that Kim had only married him for the sake of her reality TV show .