This is the story of a real uncut gem.

The Diamond District of New York City is known as a maze of jewelers, retailers, stonecutters, sellers, appraisers and a few sly snakes. “Uncut Gems,” the critically acclaimed dramedy starring Adam Sandler and written and directed by the Safdie Brothers, explores the life of the diamond district jewelers that crowd 47th street every afternoon.

The Post caught up with a Diamond-District jeweler that not only works as one of the movie’s real-life inspirations — but was also given the opportunity to be featured in the film. He recounts his accidental run-in with a casting director that led to a once-in-a-lifetime experience.

Roman Persits is a 47th street jeweler-turned-accidental part-time actor who plays alongside Sandler in the Oscar-buzzy movie. On a Tuesday afternoon, after the busy New York City lunch scene has dissipated, Roman was smoking a cigarette on the over-crowded street when a casting director took an interest in him.

“Last October, I decided to go downstairs to get a cup of coffee and have a cigarette. I was approached by a young lady who started staring at me and became speechless … I asked her, ‘Are we going to have a conversation and talk?’ She started screaming, ‘You are absolutely beautiful.’ I said, ‘… you need a new pair of glasses.’”

The casting director went on to explain to Roman that he was the exact face she needed in a new film and she wouldn’t take no for an answer. After 40-plus years in the industry and dealing with the schemers of the diamond district, Roman told us he was hesitant to agree to join this film’s cast.

Roman emigrated here in 1975 from the now-former Soviet Union, where his parents pushed him into becoming a jeweler. He got his first job at 18 as an apprentice and has been working on 47th street as a custom jeweler since he was 35 years old. It only took 30 years and many customers later for an A-list actor to come walking through his workshop doors.

“My landlord told me to be very early at work because he had a surprise for me. At 9 a.m. there is a buzz at the door. A huge gentleman walks in and says, ‘Can we speak to Roman?’ Behind him walks in a gentleman with a baseball cap, slightly unshaven, basketball shorts, T-shirt and dark glasses,” Roman, speaking in his thick accent, recalled to us. “He takes off his hat and glasses…it’s Adam Sandler. He folds his hands and says, ‘I heard you don’t want to be in my movie.’”

From then on, Roman was sold.

During filming, he was able to indulge in the brilliant minds of the Safdie brothers, who’ve also directed and written the successful and thrilling “Good Time.”

“These brothers … their adrenaline level runs on 100 percent high,” Roman said. “Sometimes we were filming from 8 in the morning to 2 or 3 at night … It was the most interesting and rewarding experience of my life. They are true professionals.”

Though Sandler’s signature witty nature shines on screen, his sense of humor translated behind-the-scenes, too, as he spent a ton of time with Roman and the rest of the cast and crew, which made the soon-to-be-famous jeweler feel like he was part of the team. Despite being hesitant to participate at first, Roman has no regrets about joining Sandler and co.

“As a jeweler who works on 47^th street, I can tell you honestly, that the movie is very true to the real thing,” he said.

DISCLAIMER: Roman Persits is Mackenzie Samet’s father-in-law.