A 62-piece collection of rare works, some unseen for decades — paintings by Vincent van Gogh, Claude Monet and Winslow Homer, and oil sketches by Georges Seurat — have been added to the National Gallery of Art.

The works are part of a 110-piece bequest by the late philanthropist Paul Mellon. After his death in 1999, they remained in the care of his wife, Rachel “Bunny” Lambert Mellon, who released 48 works during her lifetime, including van Gogh’s “Green Wheat Fields, Auvers,” which went on view last year. These final pieces come to the gallery after her death in March.

The pieces are largely intimate works, of sizes and proportions that would fill a home, said Kimberly A. Jones, associate curator of French paintings. “It’s not about the physical scale but the quality of the works, which is exceptional,” she said.

Highlights include another van Gogh, “Still Life of Oranges and Lemons with Blue Gloves,” which is undergoing conservation and will go on display next month. “The Riders” by Edgar Degas is an example of both Degas’ and Mellon’s passion for horse racing and adds to the gallery’s Degas collection, the third-largest in the world.

Twelve oil sketches by Seurat are especially significant because the artist died young and left behind a relatively small body of work, Jones said. They have been added to the two large oil paintings, two other small oil sketches and one drawing already in the gallery collection.

“These are not the works everyone else is acquiring and displaying,” Jones said, “and there’s some nice little surprises.”

There’s an early still life by Monet, an icon of impressionism. “We have 25 works by Monet, but we didn’t have an early still life,” she said. “This isn’t necessarily what collectors today might be attracted to.”

And there’s a large pastel, very rare in scale, by William Merritt Chase, a sun-drenched landscape of young girls picking flowers.

The new additions are being photographed, catalogued and, in some cases, cleaned and conserved, and visitors won’t necessarily notice an immediate bump from the bequest. The van Gogh is going on display in early June as part of an installation of his work, and the gallery is planning a 2016 exhibition to honor the Mellons.

Jones calls these last additions, which end the family’s direct donations of art, bittersweet — but a curator’s delight. Jones has been at the National Gallery of Art for 19 years but saw “The Riders” for the first time recently. Her first thought: “Wow, it’s green.”

“I hadn’t even been able to imagine what it would look like from a black-and-white photo,” she said, “but it’s so much larger and more impressive.”

To see a selection of the works, go to washingtonpost.com/goingoutguide.