PEOPLE can exclusively reveal that Melissa Rivers is donating her late mother Joan's iconic, one-of-a-kind rainbow coat to the Family Equality Council to be included in their upcoming auction.
"She would be thrilled to know that her coat, which celebrates diversity, is being sold to benefit loving families," added Melissa.
"Joan Rivers was a celebrity pioneer in her unbridled support of the LGBT community," said Ian Patrick, Deputy Director of Events at Family Equality Council. "We are honored to offer this precious piece of her legacy to support our work to secure a rightful place for LGBTQ-headed families in America."
The coat, which Joan originally wore at the Las Vegas Pride Parade in 2012, is a glittery gold gown adorned with a ruffled-neckline, and opens up to reveal a sparkly rainbow lining.
It was designed by Broadway costume designer William Ivey Long at Joan's request and will be available for bidding at the auction itself as well as online ahead of time.
The coat was part of the legendary comedian collection of unique clothing, jewelry and art, much of which will be sold at an upcoming Christie's auction in New York City on June 22.
The auction house is putting up more than 200 of Rivers' prized possessions from her Manhattan penthouse, with items ranging from $500 to $200,000, and including everything from a Tiffany water bowl engraved with Spike to an Edouard Vuillard painting with an estimated value of $120,000–$180,000.
Bids on Rivers' coat can be submitted now.