TUCSON, Ariz. — To experience the gemstone trade in all its polyglot glory, jewelers from around the world have a beloved annual ritual: For about three weeks every year, starting in late January, they flock to this city in the Sonoran Desert.

That is when tens of thousands of people with a stake in the gem business — miners, cutters, dealers, retailers, designers and collectors — arrive in southern Arizona to buy and sell colored stones at dozens of gem and mineral shows staged in hotel rooms, parking lots and tents across town.

The shows — an emporium for almost every variety of gem in the world, from $10 slabs of rough amazonite to $100,000 specimens of faceted zircon — have long attracted designers in search of building blocks for their next collections. Often clad in cowboy hats and casual denim, world-class jewelers from houses such as Boucheron and Tiffany & Company and newcomers just getting started on Etsy cruise the aisles looking for one-of-a-kind stones.

Last month, The New York Times trailed five jewelers — Robert Turner, a co-founder of Jamie Turner Designs in Austin, Texas; Katherine Jetter, an Australian designer based in Boston; Lauren Kessler, whose New York-based brand is called Lauren K; Lauren Harwell Godfrey from Marin County, California; and the London-based designer Stephen Webster — as they perused the gem selection at a handful of the 45 shows in the city.

“There are opportunities to see things here that you don’t see as much if you’re sourcing from New York,” Ms. Harwell Godfrey said. “Tucson’s got amazing vendors from all around the world. I wish I had the luxury to fly to Bangkok to look at spinels, but that’s not really my life.”

Ms. Jetter, too, comes to Tucson to see her favorite dealers, such as Mario Ikasovic, an opal specialist based in Sydney, Australia. At his booth, she held a heart-shape blue-green boulder opal worth $27,000 to the light. “It looks like the world,” she said.

For Mr. Turner, a real estate mogul who in November introduced a fine jewelry brand named for his daughter, Jamie, the gem shows are the perfect place to get lost in conversation, as he did with Lee Collins, a dealer in Reno, Nevada, who had just returned from Ratanakiri Province in northeastern Cambodia with bright blue zircons, one of Mr. Turner’s favorite gems.

“Most of them are a couple billion years old,” Mr. Turner said. “Nothing — not water, earth, sky — is as old as a piece of zircon.” Mr. Turner said that he had been collecting gems for about 30 years, but that he had avoided Tucson until 2016 because he thought it “was like a giant garage sale with geodes.”

“Then someone was like, ‘You really should go,’” he said. “I went and I was blown away.”

The tradition started in 1955, when the Tucson Gem & Mineral Society held its first buying fair. What began as a modest gathering of amateur collectors and hobbyists spawned a succession of satellite shows that have coalesced over the years into the world’s largest gathering of its kind in terms of concurrent events, said Jane Roxbury, director of gem show and convention services at Visit Tucson, a nonprofit organization, partly funded by the city, that promotes the metropolitan Tucson region. (Her title alone is an indication of how much focus this city of almost 545,000 residents places on the events.)

“Certainly, it is Tucson’s most valuable event,” Ms. Roxbury said. The city’s most recent assessment, done in 2019, said the shows’ 65,000 attendees and 4,882 exhibitors — who came from 44 countries and 44 states — had a $131 million economic impact on the city.

The rarest and most prized gems — say, pinkish-orange padparadscha sapphires from Sri Lanka, pigeon’s blood rubies from the Mogok region in central Myanmar and Windex-blue paraiba tourmalines from Brazil and Mozambique — tend to be found at a nexus of fairs in downtown Tucson.

They include the upscale GemFair, a wholesale event organized by the American Gem Trade Association at the Tucson Convention Center; the trade-only Gem and Jewelry Exchange Show, a hub for international dealers held in a tent about the size of a football field; and the consumer-friendly Pueblo Gem & Mineral Show, which sprawls across the lobby, rooms and parking lot of the Ramada Inn along Interstate 10.

Of the five designers we trailed, only Mr. Webster ventured out to the Kino Gem & Mineral Show, held in the Kino Sports Complex about five miles south of downtown. A showcase for piles of dusty rocks, taxidermy elks, dinosaur fossils, towering amethyst geodes and countless crystal oddities, Kino represents the gem shows at their scruffiest.

“I first came to Tucson in 1983,” said Mr. Webster, as he searched among Kino’s bins of rocks for rough specimens of lemon chrysoprase and Peruvian pink opal. “My first boss was a real rockhound and as a treat, he brought me here and it changed my life.

“I saw for the first time what was possible in a world of gems. And to think, I’m doing the same thing 40 years later.”