Gemfields is delighted to introduce Imboo (‘buffalo’) at its latest high-quality emerald auction, which runs from 25 August to 11 September 2025. At 11,685 carats, Imboo is the latest, and largest, exceptional gemstone discovered at Kagem Mining (Kagem), believed to be the world’s single largest-producing emerald mine. Located in Zambia’s Copperbelt Province, Kagem is 75% owned, and operated, by Gemfields, in partnership with the Zambian government through the Industrial Development Corporation.

"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," explained Adrian Banks, Gemfields’ Managing Director – Product and Sales.

"It is easy to imagine Imboo giving rise to 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," he added.

The new owner of Imboo will be offered the opportunity to deploy unique nanoparticle-tagging, courtesy of Gemfields’ longstanding partner Provenance Proof. Providing full traceability of the gemstone, even after it has been cut and polished, Provenance Proof enables future owners to be certain that their gem originated from Kagem – and that it was part of this historical find.

Kagem has earned a reputation for producing some of the largest high-quality emeralds ever found. Prior to the discovery of Imboo was the 6,225 carat Insofu (the ‘elephant’ 2010); the 5,655 carat Inkalamu (the ‘lion’ 2018); and the 7,525 carat Chipembele (the ‘rhino’ 2021). Weighing a staggering 2,337 grams – equivalent to 11,685 carats – Imboo is the largest single gemstone discovery of exceptional quality at Kagem to date.  

"In my thirty years at Kagem, I’ve rarely seen such a remarkable formation of large, high-quality crystals,” commented Jackson Mtonga, Grading Manager - Sort House, Kagem. “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,” he concluded.

The naming of uncut emeralds is a tradition reserved only for the most rare and remarkable gems. The ‘buffalo’ emerald, or Imboo (pronounced ‘im-bow’) in the local Bemba and Lamba dialects, continues Kagem’s tradition of symbolising Zambia’s wildlife heritage, and in this instance, honouring the buffalo’s determination, endurance, sense of community and, of course, its sheer size. Imboo was discovered at Kagem’s Chama pit on 3 August 2025 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 skilfully 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.

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. This creates ideal conditions for emerald crystallisation and is conducive to forming large-sized crystals, such as the three aforementioned exceptional crystals, as well as the ‘Kafubu Cluster’ (a colossal 37,555-gram cluster of emeralds found in 2022). This reinforces the geological importance of the conditions found in the Chama pit. Kagem’s Head of Geology, Hemant Azad, explained: “Each crystal tells a story of time, pressure, and elemental harmony – an ancient masterpiece revealed in our modern age.” 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.

Kagem’s Debapriya Rakshit, Senior Manager – Geology enthused: “Each emerald recovered at Kagem is a geological time capsule, brought to light after over 500 million years in darkness.”