“I think in many ways Garrard has been too understated, too shy to tell its story,” reckons Joanne Milner. “It’s been rather British in that way. It would never be about posting the names of its clients on Instagram, for example. There’s this certain level of respect, a certain sense that, rather than do the wrong thing, it would be better to do nothing.”

Milner is the CEO of Garrard, established back in 1735 and arguably Britain’s most famous jeweller. Milner knows a thing or two about decorum too, having previously been the CEO of the London institution that is Debrett’s, the etiquette guide. “Brand,” she notes, “will only get you so far, but there has to be a real business behind it. And when I joined Debrett’s it had such a strong name but nobody seemed to know what it actually did.” She added an etiquette school, foundation, business advisory service and even leather goods.

At the House of Garrard, Milner might seem to have the opposite problem: it’s quite clear what Garrard does – make gently contemporary but mostly classic jewellery for women with a certain financial clout, with pieces ranging around £8,000 to, deep breath, £80,000 – but it’s not as well-known as it might be. This is despite having been jeweller to the royal family – with Frederick, Prince of Wales, Garrard’s first royal patron the year it launched, and with Queen Victoria first appointing the company as an official royal jeweller in 1843.

It was Garrard’s job to resize the crown for each new coronation, to maintain many of the jewels that make up the monarch’s regalia – kept, of course, in the Tower of London – and to redesign the Sovereign Sceptre to incorporate the Cullinan I – at 530 carats the world’s largest clear-cut diamond. More recently, it was Garrard who made Kate Middleton’s diamond and sapphire engagement ring. There was no social media brag there but, you know, word gets around.

“Of course, it’s a real honour to serve the royal family, royal families around the world, in fact,” says Milner, sitting in the Queen Mary room at Garrard’s Albemarle Street offices and flagship store, where Queen Mary was measured for her tiara. “It adds credibility to the Garrard story. And people want a story around what they buy now. If you’re choosing between two classic cars the fact that one of them used to be owned by a someone helps your decision. And, sure, the younger royals have brought new attention to the family, and also to what they wear. And if they wear a Garrard piece that’s nice for us, not that we’d copy anything we’d made for a member of the royal family – and we do get asked.

“All that said, the royal connection is just one part of the story,” Milner stresses. “Lots of brands with heritage have made theirs up. Ours at least is real. But what you actually make still has to be right for the customer today.”

Milner, in other words, isn’t one to be easily suckered by Garrard’s fairy-tale. She’s very much a product person, a Northerner – to stereotype slightly – who, one imagines, isn’t likely to be impressed by too much fluff and marketing nonsense. She points out that Garrard is the UK’s only fully-independent jeweller, able to do every aspect of jewellery creation in-house, from sourcing stones to cutting and setting them, making the jewellery and selling it. Since taking stewardship of the business three years ago – and Milner stresses that, with a company this old, it’s not about radical overhauls but being a custodian of gentle progression – Garrard has pushed a more upbeat style, with more colour and more utility, thanks to the work of designers Sara Prentice and Claire Scott. There are only about 20 pieces per collection, so each is carefully considered. And, at these prices, they need to be.

Yes, many Garrard pieces are real show-stoppers – many of which make a highlight of the house’s signature styling, the likes of its cluster setting, diamond dots and a kind of open heart motif – and it’s hard to imagine them working outside of a red carpet/society ball setting. But many others have a less-glitzy, day-to-day wearability. Of course, this isn’t Claire’s Accessories – but Garrard has moved its pieces on so they appeal to working women, and to women who want to buy for themselves. According to the Knight Frank Wealth Report, with the high-end jewellery market having grown by 110 percent over the last decade, some 23 percent of sales are now accounted for by ‘self-purchases’.

“But even then the emotion that a piece of jewellery evokes is really important, especially because jewellery is so personal, and especially because jewellery of this kind will almost certainly be passed down through a family,” argues head of design Claire Scott. “We make one-off pieces – and our bespoke department is always busy, especially as some people leave it rather late in the day to put their order in for a special occasion, like a wedding. But it’s crucial that we also make ‘everyday’ pieces, not just crowns. That’s why ‘transformables’ are so important – so you can take the centre stone out of a tiara, and yes, tiaras are still in demand, and wear it as a pendant, for example, or the tassels from ear-rings, which gives another look.”

However refined and detailed the jewellery, of course, it still has to find a customer. So Milner has also, at last, taken Garrard into China – opening boutiques in Shanghai and Beijing – as well as a pop-up in Dubai. “The fact is that a brand like Garrard requires certain levels of wealth to enjoy, so we need to be in those regions where there is that wealth, together with the desire to invest in jewellery,” says Milner, matter-of-factly. “But it’s also hard to grow a brand internationally, and many have rushed into China, for example, and been badly burned. So I think it’s probably right that Garrard has taken its time.”

Besides, there’s more going on at Garrard than stones. Few tend to be aware of its other tidy line of business in the background, a product of the company’s origins as a silverware maker. If you want a trophy – more international, mega-bucks sporting event, than Sunday League – Garrard is the place to go. The America’s Cup, the Royal Ascot Gold Cup, cups for newer horse races in Saudi Arabia and Bahrain, even the Premier League trophy, they were all made by Garrard.

“It’s really become the place to get your trophy, such that there’s really no other contender,” says Milner. “Financially it’s an important part of the business, if nowhere near the jewellery. People are surprised there’s much money in trophies. But then all the people who win [the event] tend to want a replica – they all want a piece of the trophy in the same way as they have a piece of the horse…”

It’s perhaps too early to say whether Milner will herself be deserving of a trophy for her tenure at Garrard, but one might expect the company to become more of a household name – and not just within the royal household.

“I liked jewellery before I came here, but can’t say I knew much about it, other than that I liked to wear it,” she laughs. “But that’s how it works – I’m not trying to be a jewellery designer or a gemmologist. But I do have to empower the talented people who are. They’ve no desire to look at a spreadsheet and I’ve no desire to design jewellery. God knows where we’d end up if I did that.”