Sotheby's has unveiled one of the most valuable single-owner sales in auction history: 12 Impressionist and Post-Impressionist paintings from the collection of Nelly Arrieta de Blaquier and Carlos Pedro Blaquier, estimated at $450 million, to be sold in a dedicated evening auction in New York on November 18. Senior advisor Simon Shaw called it "the collection of the year." The top lot is Van Gogh's Chataignier en fleurs roses et blanches (1890), a flowering chestnut tree painted weeks after the artist arrived in Auvers-sur-Oise, estimated in the region of $180 million — well above his $118 million auction record set by a Paul Allen collection work at Christie's in 2022. Cézanne's Arlequin (1888–90), a portrait of the artist's son in harlequin costume and one of only two from the series not held in a museum, carries an estimate near $120 million. The group also includes Pissarro's 1898 Place du Théâtre-Français ($30–40 million, which could beat his $19.7 million record), Renoir's 1877 En Canot ($25–35 million), Degas's circa-1893 racing pastel Avant la Course ($20–30 million), a Monet Tuileries view ($15–20 million), and works by Gauguin, Sisley, Derain, Vlaminck and Toulouse-Lautrec. Most were acquired in the 1960s and '70s from London's Lefevre Gallery and had not been publicly seen for about 50 years. Sotheby's is guaranteeing the consignment and sending five works on a global preview tour through Taipei, Hong Kong and Paris. In 2023, Argentina's customs authority fined the family over exports of the works to Luxembourg, but the dispute has been resolved and the works are unencumbered, the house said. The sale continues a blockbuster season in which Sotheby's took the Leonard Lauder estate — setting a $236 million Klimt record — while Christie's landed the S.I. Newhouse collection and its $181 million Pollock.