Jennifer Hudson's Engagement Ring From WWE Wrestler David Otunga Up For Auction

Jennifer Hudson's 10-year engagement to WWE wrestler David Otunga is a thing of the past with lots of hard feelings ... and now the bling is hitting the auction block.

David had Neil Lane design the 5-carat cushion cut diamond ring for Jennifer back in 2008, which has an estimated retail value of $45K.

When they broke up in 2017, Jennifer returned the ring to David. FYI ... in legalese, an engagement ring is a "gift in contemplation of marriage." If the marriage doesn't go through, in most states the person who gave the ring -- in this case David -- gets it back.

So David has now teamed up with IDoNowIDont.com to unload it. We're told David plans to give a portion of the proceeds to a fathers' rights org.

The ring has a pretty cool history ... the pop singer wore it when she snagged a Grammy in 2009 ... a Grammy presented to her by none other than Whitney Houston. And yes, it's the real deal ... meaning it's GIA certified and comes with official certification docs signed by Lane.

Jennifer and David share a 12-year-old son, David Daniel Otunga Jr., together. Their custody war was brutal, but they both seemed to have moved on separately.