FREETOWN, Sierra Leone - A pastor working in the mines of eastern Sierra Leone has unearthed a 706-carat diamond, the government said, as experts said the stone could rank as the 10th largest ever found.
The huge diamond was discovered by Emmanuel Momoh, one of thousands of Sierra Leoneans who seek their fortunes in the informal mining sector that dominates the diamond-rich Kono region, a government statement said.
"A 706-carat diamond was presented to President Dr Ernest Bai Koroma yesterday evening," the president's office said Thursday.
"Receiving the diamond, President Koroma thanked the chief and his people for not smuggling the diamond out of the country," it added, referring to the Tankoro chiefdom where Momoh uncovered the gem.
It will be sold in Sierra Leone with a "transparent" bidding process to the benefit of the community and country, the statement said.
The government of Sierra Leone has attempted to crack down on cross-border diamond trafficking to persuade foreign investors that "blood diamonds" that fuelled its civil war are a thing of the past.
Diamond expert Paul Zimnisky told AFP that once the gem's quality was assessed it could rank "between the 10th and 15th largest gem-diamonds ever recovered."
The US-based analyst said such a find by a so-called artisanal miner, the term for workers who use basic tools or their bare hands to sift the earth, was highly unusual.
"Most recent exceptional diamond discoveries have been made by large commercial miners that mine very large volumes of kimberlite ore and process it with advanced equipment," Zimnisky said.
"Artisanal mining tends to produce smaller, lower quality diamonds because the diamonds suffer breakage and erosion," he added.
Zimnisky said the stone would likely be sold outside Sierra Leone, despite the government's assertion, for better access to buyers. Without a professional assessment of the diamond's potential flaws and colouring it is impossible to value the stone.
However, a polished stone cut from the Jonker, which is the 10th largest gem-diamond ever recovered until now at 726 carats, will go on sale in Hong Kong in May. A single 25-carat portion is likely to sell for $2.2m-3.6m, or $88,000 to $144,000 for a single carat, Zimnisky said.
A 1,111-carat diamond was discovered at a mine in Botswana in 2015, the biggest find for more than a century.
That gem is second in size only to the Cullinan diamond which was unearthed in South Africa in 1905, at 3,106 carats uncut, according to the Cape Town Diamond Museum. The Cullinan was cut into several gems, including two set into the sceptre and crown of the British Crown Jewels.
Sierra Leone's role in the diamond industry has long been controversial.
The sale of "blood diamonds" helped finance civil wars across Africa in the 1990s and often funded military dictatorships on a continent that the London Diamond Bourse estimates provides 65% of the world's diamonds.
Sierra Leonean rebels allowed traders to exploit diamond mines and ship the gems abroad via Liberia. In one of the most notorious cases, former Liberian warlord Charles Taylor was found guilty of supporting the rebels in exchange for diamonds mined by slave labour.
The district where the 706-carat diamond was discovered is where US-Belgian businessman Michel Desaedeleer, accused of enslavement and diamond trafficking during Sierra Leone's civil war, is alleged to have committed his crimes.
He died in jail in September before he could stand trial.
The death toll from Sierra Leone's civil war is estimated at 120,000 in a country that now has roughly six million people, making it one of Africa's deadliest conflicts in recent history.
