London-based Gemfields has unveiled a discovery of staggering scale in Zambia’s Copperbelt Province, an 11,685-carat emerald named Imboo, or “buffalo.” The gemstone was revealed at the company’s high-quality emerald auction, running from August 25 to September 11, 2025. Weighing 2,337 grams, Imboo is the largest single emerald of exceptional quality ever recovered at the Kagem mine, which is 75% owned and operated by Gemfields in partnership with the Zambian government through the Industrial Development Corporation.
Kagem has long been known for producing some of the world’s most significant emeralds. Among its legendary discoveries are the 6,225-carat Insofu (“elephant,” 2010), the 5,655-carat Inkalamu (“lion,” 2018), and the 7,525-carat Chipembele (“rhino,” 2021). Imboo now joins this list as the most imposing find in the mine’s history.
Adrian Banks, Gemfields’ Managing Director, Product and Sales, said, “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.”
Mr. Banks further added, “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.”
The future owner will also be offered nanoparticle-tagging technology developed by Provenance Proof, Gemfields’ long-time partner. This ensures traceability of the gemstone even after cutting and polishing, securing its identity as part of this historic recovery.
The naming of Imboo carries cultural weight. Reserved only for the rarest and most remarkable gems, the tradition continues Kagem’s practice of connecting its most valuable discoveries to Zambia’s wildlife. The buffalo, chosen for its determination, endurance, sense of community, and sheer size, symbolises the qualities embodied in the stone.
Jackson Mtonga, Grading Manager – Sort House at Kagem, said, “In my thirty years at Kagem, I’ve rarely seen such a remarkable formation of large, high-quality crystals. 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.”
The stone was uncovered on August 3, 2025 at the mine’s Chama pit by geologist Dharanidhar Seth and chiseller Justin Banda, who has played a vital role in freeing many of Kagem’s most important finds. Banda was once again the first person to bring the emerald into human contact – a responsibility regarded as crucial for the safe extraction of large crystals.
Geologists emphasise that Imboo’s formation reflects what is known as the “Tri-Junction Model,” where three different rock and structural domains intersect. This setting creates the right conditions for large emerald crystals to grow, as seen with past discoveries and the colossal 37,555-gram Kafubu Cluster recovered in 2022.
Kagem’s Head of Geology, Hemant Azad, said: “Each crystal tells a story of time, pressure, and elemental harmony – an ancient masterpiece revealed in our modern age.” Extraction at the mine relies on careful, hand-based techniques that preserve the crystal’s integrity while limiting environmental impact. “Each emerald recovered at Kagem is a geological time capsule, brought to light after over 500 million years in darkness,” he added.
With Imboo, Gemfields adds another chapter to Zambia’s role in shaping the global emerald market. Beyond its striking size, the discovery underlines the geological importance of the Kagem mine and the expertise of the team that continues to recover some of the rarest and most remarkable gemstones on record.
