A lot has changed at Tiffany since the makeover began. Namely, the company’s ownership. In 2021, after fraught negotiations, LVMH Moët Hennessy Louis Vuitton acquired Tiffany for about $16 billion. The sale was one of the largest deals ever in the luxury world, as well as LVMH’s most significant American brand acquisition to date.

In effect, the jewelry emporium became the property of Bernard Arnault, the 74-year-old founder, chairman and largest shareholder of LVMH, who recently dethroned Elon Musk as the world’s richest person, according to the Bloomberg Billionaires Index. Over three decades, he has built a kingdom of more than 75 brands, including Dior, Celine, TAG Heuer, Bulgari, Fendi, Dom Pérignon and Sephora.

As construction workers toiled away on the ground floor last week, one of Mr. Arnault’s five children, Alexandre Arnault, 30, stood near the spot where “Equals Pi,” a painting by Jean-Michel Basquiat, would go. The painting, which features a shade of blue similar to Tiffany’s signature color, appeared prominently in Tiffany’s 2021 “About Love” ad campaign starring Jay-Z and Beyoncé.

“When people enter from Fifth Avenue, they will see the Basquiat,” said Alexandre Arnault, who wore a Dior suit and Loro Piana sneakers. “It’s an important part of the Tiffany brand now.”