Kraft gave the ring as part of the All In Challenge, which aims to be the largest digital fundraiser in history by raising millions of dollars to feed the needy during the coronavirus pandemic.
The ring is from the 2016 NFL season, which ended with the Patriots beating the Atlanta Falcons in comeback fashion to win Super Bowl LI. New England had been down 28-3 with about two minutes left in the third quarter, but rallied with three touchdowns and a field goal in the final 17 minutes to send the game into the only overtime period in Super Bowl history. After winning the coin toss, the Patriots won by scoring a touchdown on their first possession.
"What could I do that would be special? I've been thinking about it for weeks," Kraft said in a video posted to social media. "I finally thought about our experience in Super Bowl LI against the Atlanta Falcons. We were down 28-3 and had 99.6 percent [odds] to lose. And we came back, and we won.
"And I thought about what is going on at this time and wanted to give something of extreme value in support of our health care workers. So I thought it would be good to give this ring, our fifth Super Bowl win, because it showed how we came back."
The 5.1 carat-weight ring, crafted with 10-karat white gold, started with a bid of $75,000 that had increased to $330,000 by Monday morning. The auction lasts for 11 days.
"We're the greatest country in the world, with the greatest people, who feel a sense of team and work together in the toughest times," Kraft added. "So I want to give this ring to someone who will be worthy enough to bid it up, so we can get meals to all these people who are hurting badly at this time."
The winner of the auction will also be flown by Kraft's private plane to receive the ring in the Patriots' trophy room at Gillette Stadium in Foxborough, Mass.
Fanatics founder Michael Rubin started the charity auction, which had raised nearly $40 million by Monday morning. Other items from the challenge include season tickets in the first 10 rows for five years, private putting lessons from Tiger Woods and an autographed jersey and cleats from Kansas City Chiefs star quarterback Patrick Mahomes.