Meanwhile, there have been reports over the past year of Zimbabweans captured and tortured for trespassing on the nation’s Marange diamond fields, some of the richest deposits in the world.

Many in the jewellery industry, including Tiffany, now refuse to buy any diamonds from mines in Zimbabwe or Angola, regardless of their standing under the Kimberley Process – an international diamond certification scheme intended to reduce the flow of conflict diamonds. The Kimberley Process itself has been widely criticised as lacking rigour.

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According to Anisa Kamadoli Costa, Tiffany’s chief sustainability officer, the complex global supply chains in the jewellery industry have yet to catch up with the growing customer demand for transparency and traceability. “As more ask, the industry will evolve and adapt to satisfy rising demands for transparency,” she says.

Scenting the winds of change, especially among younger buyers, Tiffany has also committed to 100 per cent traceability of all gold, silver and platinum used in its jewellery by the end of this calendar year. The brand now uses mostly either recycled precious metal or precious metals mined in the United States.

That diamond, however, is part of the jeweller’s heritage collection and predates the brand’s sustainability efforts. Unearthed in 1877 in the Kimberley Mines of South Africa, it is considered among the most important gemstone discoveries of the 19th century and was purchased by founder Charles Lewis Tiffany in its raw form in 1878, solidifying the brand’s reputation as a diamond authority.

Jewellers around the world are rapidly adapting to shifting customer concerns. A recent McKinsey report on watches and jewellery released in collaboration with trade publication Business of Fashion predicted a tripling of the sustainable jewellery market in coming years.

“By 2025, we expect sustainability-influenced purchases will account for 20 to 30 per cent of all fine jewellery sales (equivalent to US$70 billion to $110 billion),” the report concluded. “This would be a remarkable three- to four-times increase from 2019.”

Yet a large proportion of the world’s jewels and precious metals come from the poorest parts of the world, so sustainable pieces and transparent supply chains, which have become an important selling point, can be difficult to guarantee and maintain.

“Whenever they purchase products, they will consider whether the product provides an additional kind of value: to reduce carbon emissions and save energy.”

One of the largest jewellery groups in the world, with more than 4,800 shops globally, Chow Tai Fook is better placed than most to gauge customers’ intentions. The group formally and publicly launched a sustainability project in 2016 and these days it publishes an extensive online annual sustainability report.

“We follow the strict rules,” Wong says, adding the chain only uses traceable sources, according to United Nations regulations, and also maintains a strict internal tracking system.

The chain launched its T Mark sustainable diamond jewellery brand in 2016, he adds, and today the brand accounts for almost 30 per cent of all Chow Tai Fook diamond sales. The group’s sustainable jewellery sector is growing by double digits every year.

Chow Tai Fook has a solid sustainability business model driven more by a concern for society than by the profit motive, Wong says. “We are working hard to contribute back to society, for the betterment of the consumer. That is one of the drivers for a further step into what we call sustainable jewellery.”

The group uses mined or so-called natural diamonds rather than lab-grown diamonds, he says. “We source our rough diamonds from major mining companies and strictly follow the best practice of the industry.”

Sustainability has become a “buzzword” in many fields, he adds, and jewellery is no exception.

Kunming Diamonds is an audited and certified member of the London-based Responsible Jewellery Council (RJC), Maheshwari says, and it guarantees the diamonds it trades are “conflict-free and they don’t come from Zimbabwe”.

Global organisations such as the RJC, Diamonds Do Good and the World Diamond Council work to ensure standards are met, he says, adding that there is now auditing for many players in the industry, from companies in mining, manufacturing and trading to retailing.

The organisation says it has a 2030 Roadmap to measure the industry’s sustainability against the United Nations’ 17 Sustainable Development Goals (SDGs).

While some changes have been made to promote sustainable and ethical practices, the organisation concedes there has been a shortfall in the efforts needed to make a lasting difference in the industry.

“Whilst progress is being made globally against the SDGs,” it says, “there is collective acknowledgement that it is not yet advancing at the speed or scale required to achieve them by 2030.”