It was hard to tell if the opening of Sephora’s new store near Herald Square was a red carpet affair or a girl’s night out at the spa. A D.J. played techno-pop while guests sipped Moët Champagne and dabbed Jo Malone on their wrists. One 20-something wrapped her hair in a paper headband while an attendant dabbed cream on her cheeks. Another stood before a screen with a front-facing camera and sampled virtual eyelashes, swiping left to explore an array of styles before committing to the real thing.

“Oh! Do another!” said her friend, who was snapping photographs. “This is so much fun.”

Much has been written about the crisis in retail, with shoppers deserting department stores for e-tailers and fast fashion, if they shop at all. The beauty business, though, has not had the same fate. Prestige beauty sales in the United States rose 6 percent in the 12 months ending in February, tallying $15.9 billion, according to the market research company NPD Group. Makeup alone is up 11 percent, totaling $7.3 billion. But that industry, too, is in the midst of its own upheaval, driven in part by the success of stores such as Sephora, the No. 1 specialty beauty retailer in the world according to Euromonitor International, which tracks beauty sales.

Bloggers and YouTube stars, Instagram videos and virtual assistants are replacing department store sales clerks, whose customers now know as much as they do (or more) about mermaid eyes and ombré lips. Brand loyalty is out, replaced by Sephora’s try-more-buy-more ethos. Friends hold as much sway these days as trained experts.