The ice cool of Jessica McCormack

Jessica McCormack’s mission has always been to casualise diamonds – to push the idea that precious (and high-value) jewels should be worn every day rather than kept in a safe. The designer herself is a case in point: when we meet, she’s dressed in a grey cardigan, slouchy trousers and sandals, with a long gold chain hanging around her neck and a sparkling, diamond-studded pendant (£10,500) dangling off it – the epitome of relaxed-polished. “If you can wear a diamond with jeans, then it’s a job well done,” says the New Zealand-born, London-based jeweller. “I think translating diamonds for everyday is something we are really good at.”

It’s a proposition that has proven contagious. Since founding her brand 16 years ago, McCormack has garnered a loyal following of high-profile and celebrity clients and, in the past three years, has more than tripled the size of her business, from £9mn in 2020 to almost £30mn in 2023. She recently marked the success with a new store on Sloane Street to accompany her flagship townhouse on Carlos Place in Mayfair, and has also just announced a new CEO, Leonie Brantberg, previously Burberry’s head of strategy, to steer further growth. 

I’ve always been an outsider, staying in my lane

“In terms of financials, in the medium term, I believe we should be able to reach at least £100mn sales,” Brantberg says of the brand’s five-year goal. “The market today is polarised between commercial pieces you see everywhere and pieces taken out only for special occasions,” she adds. “You can wear Jessica to the Met – and be in great company – but also on the school run. She really gets the multi-dimensional life that people lead, and that’s why they love her.”

McCormack inherited her taste for objets from her father, who worked as an art dealer and auctioneer in Christchurch, New Zealand, where he would buy antiques and “reposition” them as desirable goods. “He had a brilliant eye and an amazing imagination, and he was always able to find something great and put it into a different perspective with a whole new story,” says McCormack. “That’s what has defined me the most creatively – my father and his possession obsession. We have the same aesthetic.”

In her early years, McCormack would go along with her dad and fill up “fishing tackle” boxes full of costume jewellery and old pounamu, a type of greenstone found in New Zealand’s South Island, and solder it together as a hobby. After moving to London aged 25, she interned at Sotheby’s, where she was “exposed to the most amazing jewels in the world – Russian crown jewels, 1920s Cartier, Lalique, things I had no idea about. It just blew my mind.”

Rose-gold and platinum Ball n Chain necklace with diamond pendant, POA

Yellow- and white-gold and diamond Carmela Diamond Spaghetti necklace, POA

Gold and diamond Forget Me Knot bangle, £15,000

Blackened-gold and diamond Gypset hoop earrings, £55,000

McCormack started her business from a small studio in Clerkenwell, and her first collection, called the Wind Up Archive, saw her taking old antique watch movements and setting them with diamonds – “very steampunky”, she says. When she moved her business to Carlos Place in 2013, she steered away from that aesthetic. Yet there’s still a punkish irreverence to her most popular designs, including the Wing of Desire earrings (£8,900), one of her earliest pieces, a diamond-studded cuff resembling the Greek god Hermes’ motif; the Ball n Chain necklace (from £9,000), a loop of orbs, designed to be worn with detachable pendants; and the Forget Me Knot bangle (from £15,000), a claw set with a 0.8ct diamond.

McCormack’s most successful designs, however, are her Gypsets, simple hoop earrings suspended with diamonds, which range in price from £3,250 to £500,000. “A diamond stud for me is almost naff and ageing, so this is my interpretation of that,” she says. The brand sells two pairs of Gypsets a day, and the style is beloved by Meghan, the Duchess of Sussex, Rosie Huntington-Whiteley, Victoria Beckham and Margot Robbie. “I’ve been obsessed [with McCormack] since first meeting her and being transported into her magical world of jewels and curation,” says Zoë Kravitz, another customer and Gypset-wearer. “Her work goes with everything, from gowns to T-shirts – it’s incredibly feminine in a relaxed way.”

The Gypset has also helped to cement earrings as McCormack’s biggest-selling category, part of her “core collection”, which sits alongside new collections, bridal, bespoke and high jewellery (which she categorises as any piece worth more than £100,000). Her latest high-jewellery collection, called Carmela, draws upon The Sopranos and features squiggly spaghetti shapes set with diamonds against blackened gold.

The new store, sitting next to Cartier and Tiffany, is set over two floors, encompassing a retail space, a library and an engagement ring “bar”, and mimics the eclecticism McCormack has come to be known for, filled with art and curiosities. Designing the interior herself, McCormack enlisted the American artist twins the Haas Brothers to create a display cloche for the window, while London-based textile artist Sussy Cazalet has created a hand-woven rug upstairs. A sweeping, curved sofa by Howe London is set against busy Schumacher wallpaper. It’s also replete with works by British sculptor Hew Locke, photographer Sally Mann and painter Frank Bowling. “I wanted to translate the magic of the townhouse, which has taken 10 years to perfect,” says McCormack. With interiors, as with jewellery, for her it’s all about the blend. “I love to show people how you can mix genres and styles and build a collection.”

She has also renovated the workshop underneath her Carlos Place townhouse, where all her bespoke and high-diamond jewels are made, to make space for the new technology she’s incorporating into her production. “I’m a very traditional, pencil-and-paper designer, which I then give to our craftspeople to make. Now we’ve introduced more digitisation – VR, CAD – and wax printing, which means we can create more exciting pieces.” The new workshop includes a bench table, designed by the Haas Brothers, and will accommodate clients keen to see the process of their jewels being made.

McCormack’s is still a direct-to-consumer business, with the exception of New Zealand design store Simon James, which is co-owned by her sister Georgina McCormack. “It was a business-defining moment, deciding not to sell wholesale, because I knew it was going to be a slower journey,” she says. “But I need to understand the woman who wears my designs, and I feel that if I get further from that through wholesaling, I could get disconnected, and then design unwearable things that won’t sell.” 

This considered approach has seen her stand out against other independently owned brands. “I didn’t have formal training, I didn’t go to any special school – I was very self-taught and didn’t really know the industry. So I’ve always been an outsider,” she says. “But I’ve always just stayed in my lane and done what I’ve felt was right.”