Christie’s has won on consignment the majority of art the architect I.M. Pei and his wife, Eileen, collected over their lifetimes, including works by Barnett Newman, Jean Dubuffet, Zao Wou-Ki and others. The collection is set to be auctioned in November and December after a global tour, and Christie’s expects the works could fetch more than $25 million.

Before he died in May at 102, Mr. Pei designed buildings around the world, among them the Louvre’s glass pyramid, the East Building of the National Gallery of Art in Washington and the Museum of Islamic Art in Qatar. The Peis developed close friendships with artists, architects, gallerists and museum directors over their 72 years of marriage. Those relationships, along with Mrs. Pei’s strong curatorial eye — she studied art and landscape architecture — allowed them to develop a sophisticated private collection. She died in 2014.

“Many collectors have advisers who assemble an excellent and diverse collection of art that appeals to them, that represents a certain period of work,” one of the couple’s sons, Li Chung Pei, known as Sandi, said in a phone interview . “In the case of my parents, these were all people they knew. These were people they associated with, people they were friends with. And as a consequence, many of these pieces were actually gifted to them by the artist, and that makes the collection very, very special and very personal.”

The 59-piece collection includes two works by the Color Field painter Barnett Newman, which were gifts from the artist’s wife, Annalee. The works, “Untitled 4, 1950” and “Untitled 5, 1950,” are from a series of paintings, some of which are in museum collections. The body of work also includes sculptures and paintings by the French artist Jean Dubuffet, who was a close friend of the couple.