
The Baroness, who enjoyed creating fantasies for her social occasions, once greeted 150 guests at a dinner (Diner de Tetes Surrealistes, whose invitations had to be read in a mirror) dressed as a stag at the kill, with a mask of towering antlers and pear-shaped diamond "tears" on her face.
At a ball she gave at Ferrieres for 1,600 people, the chateau was covered in white muslin to make it look like a huge diamond-studded cobweb. A gala for the Paris Ballet transformed the Palais Garnier into a woodland, with trees and vines climbing to the ceiling. At another function, her Bal Proust, celebrating the 100th anniversary of Marcel Proust's birth, Cecil Beaton took guests' photographic portraits.
"When she has made up her mind about something, there is nothing on earth that can deter her," her husband once said.
The daughter of Baron Egmont van Zuylen de Nyevelt de Haar, a Dutch diplomat, and an Egyptian mother, the Baroness was educated at Marymount College in New York.
On a trip to Paris shortly after leaving school, she met and married Count Francois de Nicolay. They were divorced six years later after she had met Baron de Rothschild and he, too, had decided to obtain a divorce. The Rothschilds were married in 1957 in a civil ceremony in New York - "to allow the tempest we had stirred up by a double divorce to subside a little," the Baroness once recalled.
After Ferrieres was donated to the Government, the Baroness did most of her entertaining at her Paris residence, the 18th-century Hotel Lambert on Ile St.-Louis. Her guests included a cross-section of international society, business and the arts- the Duchess of Windsor, Princess Grace, Elizabeth Taylor, Yves Saint Laurent, Oscar de la Renta and Andy Warhol.
"A good way of making people happy is to allow them to meet their opposites," she once said.
Nan Kempner, a New York socialite and a longtime friend, said, "She had enormous intelligence and curiosity and she wanted to see and do everything."
When France nationalized Banque Rothschild in 1981, the Baron moved to New York for a short time. Although the Baroness's illness made traveling difficult, she worked with an interior decorator on refurbishing their Upper East Side apartment.
The Baroness was also a major supporter of French couture and for many years was in the front row at important shows. She was president of the committee that organized the 1973 Divertissement a Versailles, an event at which American designers were not only introduced to Europeans but also upstaged their French counterparts.
by Enid Nemy, The New York Times, March 7, 1996