Jayne Wrightsman, a benefactor of the arts and grande dame of New York society whose celebrated collections of decorative and fine arts surrounded her life with grandeur and became treasures of the Metropolitan Museum of Art, died on Saturday at her home in Manhattan. She was 99.

Rudolph Netek, Mrs. Wrightsman’s general manager, confirmed her death.

The widow of Charles B. Wrightsman, an oil tycoon who died in 1986, Mrs. Wrightsman had no formal training in the arts, but became a connoisseur through decades of study, travel and experience in the field. Over many years, she and her husband gave the Metropolitan many of its most important European paintings and perhaps the finest collection of 18th-century French decorative arts in America.

Like her husband, she became a trustee of the Met. While giving millions to buy art and refurbish galleries, her involvement was often more personal. She spent many days walking through the galleries, examining paintings and artifacts, talking to curators, and analyzing the museum’s artistic needs.

In 1995, after Mrs. Wrightsman donated Delacroix’s 1835 “Portrait of Madame Henri François Riesener (Félicité Longrois)” and Monet’s “The Garden of Monet’s House in Argenteuil,” Carol Vogel, in a column in The New York Times, said she “has an eye for recognizing gaps in the museum’s collections and then filling them in.”