Written by Yasmin Khorram, CNN

It wasn't the $12,000 pink pinstripe suit or the $48,000 blue lizard jacket that raised eyebrows. After all, House of Bijan is often described as the most expensive men's clothing store in the world, and Paul Manafort was just another good customer.

It was how Donald Trump's former campaign chairman paid for these couture pieces that caught the attention of the store's 26-year-old CEO and owner, Nicolas Bijan.

"It's not typical to pay by wire transfer from a foreign bank," he said in an exclusive interview with CNN. "A majority of our clients pay by credit card. Occasionally we'll have a client who wants to pay with wire transfer. But that's unusual."

Bijan's new Las Vegas location. Credit: Peter Christiansen Valli

The wire transfers , reportedly made from bank accounts in Cyprus, were revealed during the first week of Manafort's trial on tax and bank fraud charges. The opening days of the case have centered around the defendant's reportedly lavish lifestyle.

Over a five-year period, Manafort spent a total of $520,000 at House of Bijan. But those purchases were not considered unusual enough for the store to ask Manafort where the money was coming from.

"We don't ask our clients how they come into wealth or where the money is from," Bijan said. "It's none of our business -- that would be overreaching."

A wealthy clientele

The appointment-only boutique was opened in 1976 by Nicolas Bijan's Tehran-born father, Bijan Pakzad. A universe unto itself, the House of Bijan's Rodeo Drive store is decorated with white marble floors, walls painted in the brand's signature Mediterranean yellow and a Baccarat chandelier adorned with 1,000 crystal bottles of Bijan's fragrances.

"My father always loved color, so when you walk into the store you see these beautiful French antique displays in front of Fernando Botero paintings in these color-coordinated closets," Bijan said. "When you walk in right now, there's a beautiful linen and silk yellow sports jacket displayed with a yellow flower arrangement."

House of Bijan has dressed an international clientele including the last five US presidents. Bijan said that Donald Trump was once a client of the brand's Fifth Avenue store, which closed nearly two decades ago.

Manafort's wardrobe included a $21,000 limited edition Bijan black titanium "Royal Way" wristwatch with crystal, an $18,000 suede beige coat and 18 cotton shirts, in assorted colors, bought for $24,600. Not to mention five silk tie sets costing $6,700.

"To be honest with you," Bijan said, "I think I can fairly say we never even knew what he did for a living."

While Bijan claimed that Manafort wasn't a top spending client, his purchases date back decades.

"He was a regular and longtime customer," Bijan said. "You can see he has pieces from many years ago, from the 80s and 90s, and even recent pieces that we designed for his collection."

Internal records, submitted to the court by House of Bijan and as seen by CNN, show that the company's general manager traveled to The Peninsula hotel in New York in April 2011. Manafort ordered $64,700 worth of clothing from the brand's employee during the trip.

"We visit our clients all over the world if they're not available to visit us on Rodeo Drive," Bijan said. "In the last year, I was in Abu Dhabi several times, Jakarta, Indonesia and London quite frequently."

By appointment only

House of Bijan recently expanded its brick-and-mortar presence, with stores opening in the Wynn Las Vegas casino resort and the Waldorf Astoria in Beverly Hills last year. But while these new shops accept walk-in customers, the Rodeo Drive flagship remains appointment-only.

"This is a very unique business; we may have two clients per day in the boutique," Bijan said. "If we have more than one client in the boutique at the same time, it's chaos."

On any given day at the House of Bijan, you may see a Rolls-Royce or a pristine Bugatti parked up outside. The oval-shaped, ivy-lined entrance opens into a cozy two-floor boutique.

Bijan's appointment-only boutique was opened in 1976. Credit: Bijan

Once inside, an 18th-century French armoire at first appears to be another piece of furniture. But Bijan's father removed its back and converted it into a secret door that leads to a dressing room.

"That's just part of the shock value we (offer) our customers to make them smile or laugh," Bijan said.

All of the clothes sold by Bijan are manufactured by hand in Tuscany, Italy. T-shirts start at $700, tie sets go for $950. Exotic animal skin items can sell for as much as $100,000.

"My father always taught me that (our brand) is not rich enough ... to make things cheap," Bijan said. "There's a lot of mystery behind our brand and a lot of people who criticize Bijan are people who don't understand, because they've simply never been here."

One-of-a-kind items

For those who have shopped at House of Bijan, it's unlikely they'll see someone else walking around in the same outfit.

"We only make one or two of each piece," Bijan said. "That way you know there's only one or two in the world, and most probably you'll never see someone wearing the same tie as you. For us men -- don't ask why -- psychologically that means a lot to us."

Bijan took over the company after his father died in 2011, dropping out of California's Pepperdine University to devote himself to the business full time.

All clothes sold by Bijan are manufactured by hand in Tuscany, Italy. Credit: Bijan

"Every man misses his father," Bijan said. "I would love to share details about my life and the business with him. I lost him at a very young age."

Today, Bijan estimates the store is one of the highest -- if not the highest -- selling store on Rodeo Drive, per square foot. The company does not disclose its revenues.

Whether dressing a president or the president's former campaign chairman, the brand remains neutral when it comes to politics, according to Bijan.

"We don't have partisan issues at Bijan," he said. "Our politics is fashion."