Gemfields Unearths Record-Setting 11,685-Carat 'Imboo' Emerald in Zambia

Gemfields has announced the discovery of the largest emerald in its history — an extraordinary 11,685-carat rough gemstone named Imboo, meaning “buffalo” in the local Bemba and Lamba dialects. Unearthed on August 3, 2025, from the Chama pit at the Kagem mine in Zambia, Imboo weighs an astonishing 2.3 kilograms (5.15 pounds) and surpasses all previous emeralds recovered by the miner.

This monumental find is being offered at Gemfields’ latest high-quality emerald auction in Bangkok, which runs through September 11. While Gemfields traditionally does not release individual lot valuations, industry observers suggest the gem could yield multiple fine-quality emeralds of significant size — potentially enough for a complete high-jewelry suite.

Imboo now tops a remarkable lineage of record-breaking emeralds recovered from Kagem, the world’s single largest emerald-producing mine. The Chama pit has been the source of several iconic 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.

The Chipembele was later certified by Guinness World Records in 2022 as the largest uncut emerald crystal recovered from a mine. With Imboo, Gemfields has once again redefined the scale of possibility in Zambian emerald production.

The tradition of naming such extraordinary finds after animals native to Zambia reflects both cultural pride and the connection between the natural world and the treasures it produces. In keeping with that tradition, the “buffalo” name underscores the emerald’s sheer size, strength and rarity.

“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 of product and sales.

Kagem’s grading manager, Jackson Mtonga, added: “In my 30 years at Kagem, I’ve rarely seen such a remarkable formation of large, high-quality crystals. This is a true masterpiece carved by nature’s hand.”

The eventual buyer of Imboo will have access to Provenance Proof’s nanoparticle-tagging technology, ensuring that the gem remains traceable to the Kagem mine even after it is cut and polished. This innovation provides a lasting record of origin and links the stone permanently to this historic discovery.

Gemfields operates Kagem in partnership with Zambia’s Industrial Development Corporation, with the government holding a 25% stake. The mine, located in the Copperbelt Province, continues to secure Zambia’s position as one of the world’s leading emerald producers, second only to Colombia.

Credit: Image courtesy of Gemfields.