The longtime Manhattan penthouse of Maurice Tempelsman, the Belgian-born diamond magnate who was Jacqueline Kennedy Onassis’s companion for more than a decade, is now on the market, nearly nine months after his death.

The asking price for the co-op apartment, atop 1155 Park Avenue in the Carnegie Hill neighborhood of the Upper East Side, is $5.5 million, with about $8,027 in monthly maintenance.

Mr. Tempelsman, who died in August 2025, three days before his 96th birthday, bought the prewar penthouse, overlooking Central Park and the Jacqueline Kennedy Onassis Reservoir, in October 1999. He paid $3.3 million.

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Jacqueline Bouvier Kennedy Onassis and Maurice Tempelsman had been companions for more than a decade. Credit...Kyle Ericksen/WWD, via Penske Media, via Getty Images

Years before, he and Mrs. Onassis had lived together in her Fifth Avenue apartment. Then after her death in May 1994, he rented a suite at the nearby Sherry-Netherland hotel, according to his son, Leon Tempelsman, the president at Lazare Kaplan International, the diamond importer where his father was chairman. (Mr. Tempelsman also had two daughters, Rena and Marcy.)

The search for a more permanent residence for his father had been a long one. “We looked at so many places — uptown, downtown, East Side, West Side, even townhouses,” Leon Tempelsman said. “We were just about ready to give up when we found this apartment.”

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