A handful of huge diamonds has arrived in the world of high jewelry that could alter the entire business.

In January 2020 Louis Vuitton, the world’s most valuable luxury brand, revealed it had bought the second- largest rough diamond ever mined. It bought the 1,758-carat Sewelô for an undisclosed amount in collaboration with Lucara Diamond Corporation, the Canadian company that owns the mine in Botswana where it was discovered, and HB Company, a diamond-manufacturing business in Antwerp, Belgium.

But it turns out the brand’s appetite for great big diamonds was just beginning. In November, it purchased a smaller, but still uncommonly large, rough diamond, the 549-carat Sethunya. Its mining partner Lucara has proved particularly adept at finding such stones. It is at the forefront of using X-ray transmission technology to locate the diamonds before they’re broken into small pieces during the ore processing and has a special Mega Diamond Recovery circuit dedicated to the search.

The acquisitions are compelling evidence that Vuitton, the star of the sprawling LVMH Moët Hennessy Louis Vuitton luxury conglomerate founded by Bernard Arnault, is polishing its high jewelry credentials. And it is not alone.

“Several luxury players are planning to enter or further penetrate the high jewelry category,” Achim Berg, head of McKinsey & Company’s apparel, fashion and luxury group, wrote in an email. “Jewelry is considered a potential growth segment for the future. The majority of that segment is unbranded and luxury brands feel that they could change that. By acquiring exclusive and very large stones they get a lot of publicity and customers who otherwise would not have thought of these brands for high jewelry.”

And while the pandemic has upended lives around the world, the clients who want to spend hundreds of thousands — or even millions — on high-end jewelry have largely been insulated from its effects. “After the last financial crisis, demonstrating wealth through spending on luxury goods was seen as vulgar and insensitive in many places,” Mr. Berg wrote.

“So far, we cannot see that effect during the course of the pandemic. In many developed regions, the middle class and the affluent have been less affected,” he added. “To the contrary, many have increased their savings rate due to lack of opportunity to spend (no travel, no restaurant visits, etc.). Therefore, spending money on luxury goods is seen by many as a reward.”

Louis Vuitton introduced its first high jewelry collection in 2009, but the diamonds represent the first opportunity for clients to participate in the entire bespoke process: from the rough stones all the way through working on final designs with Francesca Amfitheatrof, Vuitton’s artistic director of jewelry and watches.