The rising popularity of lab-grown diamonds has caused a big fall in the price of the mined gems. In the West African nation of Sierra Leone the country's biggest diamond mine has closed.

Stripped to the waist, men toil in the heat of the sun. The mud in the pit is sifted and shovelled.

Daniel, the foreman in this remote, informal, small-scale mine in Kono, the diamond region of Sierra Leone, shows me the gravel he's picking through with his fingers.

"We put it in water and we wash it," he says. "If there is anything like a diamond or any bright stone, we can see it."

Daniel and five others are searching for just tiny fragments, but pickings are thin. "I have not made a lot of money yet," he says. "Sometimes for the whole of the year you can't get anything.

"It is by the grace of God that you find a diamond. We are just dreaming, really. We still have that hope."

Such informal mining has increased in Kono following the closure last year of the country's biggest diamond mine Koidu Holdings. It shut with the loss of 1,000 jobs after a bitter industrial dispute over the miners' pay.

Officially the company says it closed due to the cost of the dispute and security concerns, but privately, insiders also acknowledge that the weakness of the global market also played a role.

In just the past four years, the retail price of polished natural diamonds has fallen some 40%. The main driver has been the rapid growth of the so-called lab-grown diamond industry.

These factory-made diamonds, produced from crystalised carbon, are chemically and physically identical to mined diamonds.

Manufactured mostly in India and China using two different technologies – HPHT (high pressure high temperature) and CVD (chemical vapour deposition) – they cost a fraction of the price, up to 70% less.

Kono's governor, Augustine Shekho, says the big fall in the global price of natural diamonds has hit the region hard over the past five years. "Lower diamond values have reduced earnings for miners, constrained investment, and weakened local economic activity."

Lab-grown diamonds have the same chemical composition as those naturally formed

Diamond mining has been the lifeblood of this part of West Africa since the 1930s. Thirty-five years ago it became the focus of a brutal, long-running civil war in Sierra Leone, immortalised by Leonardo Di Caprio in the 2006 Hollywood film Blood Diamonds.

Kono was a target because of its diamond wealth. Shekho described multiple atrocities committed in the region, including the killing of his own mother, as armed factions traded control.

"They shot at random, they killed people, burnt the entire town," he says. "All houses were mined.

"It was a war of terror... She, my mother, unfortunately, was the victim of that… It was a nightmare. I would really not want to think about it."

It's estimated that by the end of the 11-year conflict, more than 50,000 people had died, and hundreds of thousands more were maimed or displaced.

Informal, small-scale diamond mines are a common sight in the Kono region

In 2003, a United Nations-backed international diamond certification scheme, the Kimberley Process, was launched in order to prevent conflict stones from entering the mainstream diamond market. But the industry has struggled to contain the reputational damage.

"To me the diamonds have failed us," says Abubakar Amara, a primary school teacher in Kono. "What have those diamonds done for our community, for Kono, for Sierra Leone? We are considered as poor in the world."

The British multinational, De Beers, which specialises in the mining and marketing of diamonds, is eager to change the narrative. In Sierra Leone, it's launched a project called Gemfair, where local artisanal miners are offered equipment, training, and more transparent pricing for their finds. You might call it a kind of fairtrade scheme for diamonds.

"The idea is to connect with markets so that they can be able to find a place to sell their diamonds, and also to empower them, give them training, we give them skills," says Raymond Alpha, Gemfair's local representative.

But for De Beers, perhaps its most important function is reputational, allowing retailers to tell the origin story of every diamond they sell.

"We are seeing a growing interest from consumers," says David Johnson, a De Beers representative. "With people increasingly wanting to know where their coffee, cotton or chocolate has come from, it's not surprising that people also want to know where their diamond – one of the most emotionally significant purchases – has come from."

While this increased traceability could win mined diamonds more customers, others say that the lab-grown alternatives are only going to continue to grow in popularity.

Rohit Mehta, chief executive of Forlink Ventures, a commodities house based in India's lab-grown diamond capital, Surat, says these diamonds are not just cheaper, but also more ethical and better for the environment.

"People are more conscious about climate change, about extracting too much from the earth," he says.

But the argument that lab-grown diamonds are "green" doesn't sit well with everyone. Unlike natural diamonds, the lab-grown variety are hugely energy-intensive, requiring vast amounts of electricity to produce a single rough carat.

"These reactors run at the temperature of the sun," says Stanley Mathuram, a US-based environmental consultant who's studied the growth of the lab-grown diamond industry. "They're like data centres. That's the kind of energy that they require."

A growing number of people are buying engagement rings made with a lab-grown diamonds

However, that concern about energy consumption does not appear to be putting off buyers. The global lab-grown diamond market was valued at $29.5bn (£21.9bn) last year, and is tipped to grow to $91.9bn by 2034, according to one study.

The lab-grown figure for 2025 is already above the $20bn that De Beers estimates is the total, international annual value of natural, mined diamonds used in jewellery.

In the US, engagement rings with lab-grown stones now account for 61% of all sales, according to the 2026 Real Weddings Study by wedding planning website The Knot.

The report said this was a more than two-fold increase since 2022, with lab-grown diamonds by far the most popular choice. It said the shift was "driven by economic pragmatism and evolving values, with 40% of couples stating it is specifically important that their stone be lab grown".

Doug Meadows, co-founder of David Douglas Diamonds, a jewellery retailer in Atlanta, Georgia, says that people are going lab-grown as it means they can afford a bigger stone.

"It's all about the stone. They're going for the biggest bling that they can afford. Years ago, it used to be the diamond was the expensive part.

"With the advent of gold jumping up to $4,500, $5,000 an ounce, now the mounting is becoming a lot more expensive, and the diamond is becoming the cheap part."

Meadows adds that he is sympathetic to the idea of promoting natural diamonds, with a story rooted in the soil, and the experience of poor miners in West Africa. But it's a hard sell.

"To try to educate a consumer about the value in a natural diamond, it is a new challenge. I don't know how we do it yet, I'm hoping the industry can give us an idea."

Back in the diamond belt of Sierra Leone, Daniel discards another sieve-load of gravel.

"Unfortunately there is no diamond here," he says, head bowed, gazing into the blue-grey mud of the pit. "I will try my luck again," he adds as he resumes digging.