There are two Sierra Leones in the diamond world. Two realities so different it's hard to believe they come from the same country.
The first: white diamonds of a purity and luminosity few origins in the world can match. Smooth, transparent crystals, a clarity diamond dealers recognise at first glance.
The second: a yellow so saturated, so deep, so unique that it ended up carrying its own name around the world. The Zimmi.
Two stones. Two legends. One country.
The Lebanese, builders of West African diamond trade
Before talking about the stones, we need to talk about the people.
There's a story few diamond sources tell, but that every diamond dealer who has worked in West Africa knows. In the early twentieth century, waves of migrants left villages in southern Lebanon for South America, the promise of a new world, a possible trade, a better life. Their ships crossed the Atlantic. But many never reached their destination.
The boats stopped in West Africa, in Sierra Leone, Senegal, Côte d'Ivoire, for technical stops, navigation issues, reasons history hasn't fully recorded. And some of these migrants stayed. Because they couldn't afford to continue. Because they found opportunities. Because Africa, sometimes, holds on to those who touch it.
These Lebanese families, settled for generations, did what good traders do everywhere: they adapted. They learned local languages, built relationships, understood the markets. And very quickly, they became the essential intermediaries of the rough diamond trade in West Africa, in Kenema, Bo, Koidu in Sierra Leone, Abidjan, Dakar.
Their network extended all the way to Zaire, now the DRC, where Lebanese families have been settled for decades in Kinshasa and diamond-producing towns. A trading diaspora, discreet, skilled, that built much of the informal infrastructure of the rough diamond trade in Central and West Africa. Their role is often underestimated in official industry analysis, on the ground, it's central.
The districts, Kono, Kenema, Bo
Sierra Leone's diamonds come mainly from three districts in the east and south-east of the country, drained by the Sewa, Bafi, Moa, Woa and Mano rivers.
Kono, the historic heart, in the east of the country 330 kilometres from Freetown. This is where the first alluvial discoveries took place in 1930. The Koidu Limited kimberlite mine has operated here since 2002. Artisanal mining employs tens of thousands of people.
Kenema, further south, in the eastern province, another historic centre of alluvial production and trade. A town of diamond dealers, traders, Lebanese merchants settled for generations.
Bo, in the southern province, smaller in volume but present in the local value chain.
Crystal white, what makes Sierra Leone recognisable
The vast majority of Sierra Leone's diamonds are crystals, stones of crystalline formation, whether perfect octahedrons or flattened. What unites them all is that smooth-faceted appearance, like glass cut by nature itself. A brilliance, a clarity, a transparency that belongs to them alone.
You can recognise a Sierra Leone diamond. A professional who has held these stones doesn't mistake them for an Angolan, Congolese, or Namibian one.
Some stones are perfect octahedrons, two pyramids fused at the base, with smooth, glossy triangular faces. Others are makeable or sawable, less regular shapes but workable. And many are coated, covered in a slightly green to light yellow skin, sometimes on one face only, sometimes over the whole surface, sometimes remarkably thick. Beneath that skin, a clean stone can be hiding.
That green or light yellow coating tint is a signature. It comes from natural irradiation, the diamond in contact with the soil over millions of years absorbs radiation that colours its surface without touching the interior. Once cut, the colour disappears. What remains is the purity of a Sierra Leone crystal.
The Star of Sierra Leone, 968.9 carats, discovered on 14 February 1972 in the alluvial mines of Yengema near Koidu, is the largest gem-quality alluvial diamond ever found on Earth. A colourless, transparent crystal of rare perfection. It was entrusted for cutting to master Lazare Kaplan, who studied the stone for over a year before cleaving it live on American television in August 1973.
The diamond war, and its aftermath
It's impossible to talk about Sierra Leone without mentioning the decade of civil war that bloodied the country from 1991 to 2002. Blood diamonds financed the RUF and its atrocities against civilians. The Kimberley Process, born in 2003, partly originated in this country.
Today, Sierra Leone is a signatory of the Kimberley Process. Artisanal mining produces about 40% of the country's diamonds. The road has been long. It isn't finished.
The Zimmi, a colour, a territory, an absolute rarity
250 kilometres south of Kono, in the district of Pujehun, on the border with Liberia, where the Mano river marks the divide between two countries, that's where Zimmi is found. A village. A 25-square-kilometre zone. And the most sought-after yellow colour in the world.
The Zimmi is a Type Ib diamond, nitrogen present as isolated atoms in the crystal lattice, not in pairs as in other yellow diamonds. This configuration absorbs light differently. It creates a yellow of a saturation and depth the GIA classifies as Fancy Vivid, but that visually surpasses anything else that category produces elsewhere. In the old days, it was called canary yellow. Today, people just say Zimmi, and the word is enough.
But here's what many don't know: the Zimmi isn't a perfect stone. Far from it.
The rough shape is often makeable or flattened, not the regular octahedron that gives a high yield. Cutting yield is therefore often low. And clarity? That's where the rarity becomes absolute. A clean Zimmi, free of inclusions, free of pits, of acceptable clarity, is extremely rare. Many Zimmis come out pitted or low clarity. The colour is there, intense, extraordinary. But clarity doesn't always follow.
That's precisely why a high-clarity Zimmi reaches prices nothing else in the world reaches in its category. Colour alone is exceptional. Clarity alone from this origin is exceptional. The two together, it's one of the rarest diamonds that exist. One in ten thousand carats extracted is a natural fancy colour. And among those, the clean ones can be counted on one hand.
The flip side of the Zimmi is exactly that, colour on one side, compromises on the other. But when the two align, there's nothing comparable.
Laurent de Toledo is a third-generation independent diamond dealer, HRD Certified Diamond Grader, trained at the Harry Oppenheimer Diamond Training School in Johannesburg. Nearly 30 years in diamonds, including 20 years buying rough in Angola and the DRC.