Gemstone miner Gemfields has mined its biggest emerald from its Kagem Mining operation in Zambia, which it has named Imboo (meaning Buffalo) and which went on auction on September 11, the sales proceeds of which being repatriated to Zambia.

At 11 685 ct, Imboo was discovered at Kagem’s Chama pit on August 3 by geologist Dharanidhar Seth – a seasoned expert with over a decade of experience, and Justin Banda – a veteran chiseller who has been instrumental in many successful recoveries of noteworthy gems by skillfully breaking them free from the surrounding matrix.

The first human being to come into contact with the gemstone is also perhaps the most critical in ensuring its successful recovery, states Gemfields in a statement, adding that Imboo is the biggest single gemstone discovery of exceptional quality at Kagem to date.

The recovery of Imboo also highlights the expertise and care of Kagem’s team, who use gentle, hand-based extraction techniques to preserve crystal integrity and minimise environmental impact.

“In my 30 years at Kagem, I’ve rarely seen such a remarkable formation of large, high-quality crystals,” says Kagem sort house grading manager Jackson Mtonga, adding that the immense size and nature of the crystal formation makes it fitting that this unique piece is given the name Imboo in Zambia’s local languages of Bemba and Lamba.

“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,” explains Gemfields product and sales MD Adrian Banks.

He adds that Imboo will most likely produce several fine-quality cut emeralds of significant size.

“Such a rare collection could form an entire high jewellery suite from this single gemstone. This remarkable find may tempt its new owner to see it not only as a source of extraordinary gems, but as a unique investment destined to be remembered in the annals of exceptional emeralds,” adds Banks.

The complex geological setting of Imboo’s discovery presents a classic example of the Tri-Junction Model, where three distinct lithological and structural domains converge, thereby creating ideal conditions for emerald crystallisation and being conducive to forming large-sized crystals.

The naming of uncut emeralds is a tradition reserved only for the most rare and remarkable gems, states Gemfields.

Prior to the discovery of Imboo was the 2010-found 6 225 ct Insofu (meaning Elephant); the 2018-found 5 655 ct Inkalamu (meaning Lion); and the 2021-found 7 525 ct Chipembele (meaning Rhino).

“Each emerald recovered at Kagem is a geological time capsule, brought to light after over 500-million years in darkness,” says Kagem geology senior manager Debapriya Rakshit.