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.
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.”
He said Mr. Tempelsman was immediately struck by the grand scale of the rooms in the penthouse and the enormous wraparound terrace. At around 3,660 square feet, it is nearly twice the size of the actual unit.
“He was walking through the apartment with the broker trying to put on a game face, then he turned around with his hand cupped over his mouth and said, ‘I love it,’” his son recalled. “It was love at first sight.”
The penthouse has roughly 1,872 square feet of interior space, with two bedrooms, one of which was turned into a library, three and a half bathrooms, and a staff room that could be converted into a home office or breakfast nook. There’s also a laundry area.
Mr. Tempelsman kept the layout intact, and aside from painting and adding wallpaper, made few changes to the interior space, which he decorated with traditional furnishings and classic American art from the late-18th to early 21st centuries.
“The biggest change was the elaborate build-out of the garden,” his son said. “It was nowhere near as heavily planted.”
Entry to the home is on the 12th floor. A private foyer has a set of stairs leading up to the unit’s spacious dining area. The room is surrounded by floor-to-ceiling windows and features French doors that open to the park-facing west side of the terrace. Nearby is a windowed galley kitchen and staff bedroom.
Beyond the dining area is a large living room anchored by a wood-burning fireplace with a carved wooden mantel and marble surround.
The primary bedroom suite includes two walk-in closets and an en-suite tiled bathroom. The library, also with an en suite bathroom, has a wall of built-in bookshelves.
Throughout the apartment are hardwood floors, high ceilings and oversize windows. And nearly all the rooms have access to the exterior, even the staff quarters.
“There’s a seamless flow between the indoors and outdoors,” said Allison Bandier Koffman of Sotheby’s International Realty, who is listing the penthouse with her colleague Juliette Janssens.
“The exposures are spectacular,” Ms. Janssens said. “You get city and Central Park views. You can see the reservoir. And you can even see the East River.”
The irrigated rooftop terrace, which features a fountain with koi fish, is lined with concrete pavers and brimming with potted plants, flowers and trees. Among them: Japanese maple, weeping cherry and crab apple trees, dogwoods, wisteria and English ivy.
Mr. Tempelsman enjoyed reading on the terrace, his son said, and would often entertain there, sometimes on a grand scale, in addition to hosting intimate dinner parties inside.
“He would have dignitaries and political figures visit him and you would have these Secret Service sweeps,” Leon Tempelsman said. Many of the guests were from Africa, where his father had frequent business dealings as a gem importer. Mr. Tempelsman would also hold gatherings for the charities he supported, like the Corporate Council on Africa and the Woods Hole Oceanographic Institution, he added.
The terrace has several areas carved out for lounging and dining, and something you probably won’t find anywhere in New York: a wooden skiff from Martha’s Vineyard.
“He loved telling people about the vertical journey involved in hoisting a 13-foot boat up 12 floors to the top of a New York City building,” Leon Tempelsman said. “This is most likely the first penthouse apartment to come with its very own skiff.”