Gemfields’ massive 11,685-carat ‘buffalo’ emerald set for auction

[Ben Graham]

Coloured precious stones miner Gemfields (LON: GEM) (JSE: GML) has unveiled a colossal emerald weighing 11,685 carats, discovered at its 75%-owned Kagem mine in Zambia.

Named Imboo, meaning buffalo in the local Bemba and Lamba dialects, the gemstone is the largest of several extraordinary emeralds unearthed at Kagem, already famed for record-breaking finds. The emerald will be sold at Gemfields’ auction running until Sept. 11.

“Even under the beam of a strong light that is necessary to illuminate a gemstone of this remarkable size, Imboo reveals an intense, verdant green touched with golden warmth and a clarity that captivates the eye,” Gemfields’ managing director of product and sales, Adrian Banks, said.

Banks added the stone could yield multiple fine-quality emeralds large enough to form a complete high-jewellery suite, or serve as an investment destined for the history books. 

Bigger, greener, rarer

At 2,337 grams, Imboo surpasses the mine’s earlier discoveries: the 6,225-carat Insofu (“elephant”) in 2010, the 5,655-carat Inkalamu (“lion”) in 2018, and the 7,525-carat Chipembele (“rhino”) in 2021.

Discovered on Aug. 3 at the Chama pit, the emerald was first freed from rock by geologist Dharanidhar Seth and chiseller Justin Banda, whose precise extraction was crucial to preserving the crystal. The complex geological setting, known as the Tri-Junction Model, where three rock and structural domains converge, creates ideal conditions for emerald formation. Similar geology produced the “Kafubu Cluster,” a 37,555-gram emerald grouping found in 2022.

“In my thirty years at Kagem, I’ve rarely seen such a remarkable formation of large, high-quality crystals,” grading manager Jackson Mtonga said. “The immense size and nature of the crystal formation makes it fitting that this unique piece is given the name ‘buffalo’, or Imboo in our local languages. This is a true masterpiece carved by nature’s hand.”

Traceable

Gemfields’ partner Provenance Proof will offer the new owner nanoparticle tagging technology, providing permanent traceability of the emerald even after cutting and polishing. This ensures its origin at Kagem remains verifiable.

Zambia, the second-largest emerald producer globally after Colombia, holds a 25% stake in the Kagem mine through its government.

Outside Zambia, Gemfields owns a 75% stake in the Montepuez ruby mine in Mozambique.