The Top Lots From 2 Private Collections Heading to Auction in May

There’s always something a little magical about a single-owner sale in the auction world, from the dissemination of the Duchess of Windsor’s history-laced jewelry in 1987 to the court-ordered breakup of warring exes Harry and Linda Macklowe’s nearly billion-dollar art collection in 2021 and 2022. 

Next month, both Christie’s and Sotheby’s are hawking storied troves, one an enviable assemblage of modern art by some of the past century’s preeminent names, the other a…