LONDON — What sparkles come rain or shine?

For fine jeweler Jessica McCormack — who has just set up her first international outpost on Madison Avenue neighboring a string of luxury brands including Chanel, Boucheron, Pomellato and Bottega Veneta — it’s diamonds.

The London-based designer has brought a taste of home to the store with oakwood furnishing and trims that can be found in her brand’s flagship on Carlos Place, as well as artwork from her kitchen and store.

McCormack is ensuring everyone knows she’s in town. There’s allure and personality for any passerby — it’s hard to miss the colorfully hand-painted mural of Madison Avenue with quirky floral and canine details.

“We’re a small London brand, people don’t know who we are in America compared to the 200-year-old brands — just the idea of somebody walking past our store, they need to be intrigued to look inside and think, ‘wow, that’s really fun and joyful.’ I sometimes walk around shops and it can all feel quite the same,” she said in an interview.

“Having a look at a lot of the shops here [in New York], they look very corporate and it doesn’t make me want to go in there,” she added.

The only gray that McCormack has brought with her is perhaps the British weather, but other than that, everything follows a European sensibility. The store is in a Beaux-Arts building from 1879 with 3,200 square feet and two floors.

There’s enough room for all of the diamonds to breathe and shine, from everyday diamond Gypset drops; the newly launched Fruit Salad collection to the 20-carat Ellipse Diamond Torque necklace.

The artwork covering the walls is expansive.

Valérie Belin’s “Amazon Lily (with Garden Roses)” is one of the pieces that commands attention with its floral layers on a ‘50s-style model wearing a double strand of pearls. Other artwork include David Salle’s line drawing using ink; Girolamo Marchesi da Cotignola’s “The Visitation,” depicting the meeting of the Virgin Mary and Elizabeth, mother of John the Baptist, during their pregnancies, and sculptures and objects from Tanzania, Nigeria, Cameroon and Sierra Leone.

The touches of artwork and vintage furnishing are sentimental to McCormack, whose father was an antiques and art dealer. In one corner there’s a beer stool that’s actually a music box, while in another part of the store there’s a Sabine Marcelis perspex mirror, which she also has in her London store.

Some of the pieces are even displayed on totems similar to the ones at Carlos Place.

“We’d come home and there’d be crazy things [my father bought] and then a few months later he’d sold it and there’s a piece of furniture missing. He was always recreating spaces; it’s not just about having expensive pieces, it’s about the mix and the genre of how you collect things. I feel our style is quite unique and that’s the same with the jewelry,” said McCormack.

She follows the same approach when advising her clients by suggesting they shouldn’t buy all their jewelry from one jeweler.

McCormack’s infectious charisma makes her a natural shopkeeper and she enjoys interacting with her customers as it leads her designs.

“For me to know what women want to buy and how they wear things, I have to do that physically. We have a great business online and it’s super healthy and self-sufficient, but it’s all about the feedback from the women buying these pieces,” she said.

When designing jewelry, she asks herself questions such as “do I want to spend my money on this? Do I want to wear it all day? Is it comfortable? Does it bring me lifetime or multiple lifetimes of joy? If my children see me wearing something all the time, is that something that they will love as well?” 

McCormack’s diamonds are an investment and not a cheap one.

Her prices start at 1,625 pounds for a 0.20 carat diamond and white gold single Gypset hoop earring and can fetch into the millions for a 53-carat diamond button-back necklace.

In November last year, McCormack received new investment from Lingotto Horizon, which is owned by the Agnelli family’s Exor holding.

The investment has been used to build out the Jessica McCormack retail portfolio. The brand also has a second store on Sloane Street in Knightsbridge and entered Harrods in September last year.

“We want to grow the brand, but we want to do this in a very careful and considered way. No one’s on my back as CEO saying you’ve got to open 20 stores a year. We have a handful of stores, let’s say less than 10 that we’re planning for the foreseeable future,” said the brand’s chief executive officer Leonie Brantberg.

“We have our eyes on the U.S. as the next horizon, but it’ll be really interesting to see what happens with Harrods, as we’re seeing so many different clients from the Middle East, Asia and India, that we haven’t really had [much contact with]. It’ll be really interesting to take the market data from that and inform where we can go next,” she added.

Americans make up about a third of Jessica McCormack’s customer base and it’s a market that cares about wearing diamonds, according to Brantberg.

“There’s some really interesting demographics that are going on there. The great wealth transfer that’s about to happen [for women with] over $50 trillion going down generations. This historic percentage of women that are now going to inherit are crying out for women-led diamond jewelry brands,” she explained.

The brand has also teamed up with a local atelier in New York City that have been trained by McCormack for repairs and alterations. 

The U.K. still remains as the brand’s biggest market because of its presence in the country. 

Jessica McCormack is also launching into partnerships with Net-a-porter and Mytheresa on small pop-ups to test the waters for the larger European market.

Brantberg wants to reach the right clientele. 

“Ubiquity isn’t always a great thing in hard luxury because if you’re buying an engagement ring, you don’t want to know that that ring is available in every like airport in the world,” she said, adding that the brand’s average transaction value is between 15,000 to 20,000 pounds with 50 percent of the purchases being made by women who are buying day diamonds for themselves.

In the last quarter, the brand’s sales have grown in the triple digits and they have welcomed a “higher portion of new customers” according to Brantberg.

Jessica McCormack’s Madison Avenue store is just one stop on the brand’s deliberately curated Monopoly board.