Karowe Underground Project Reaches Full Shaft Depth, Paving the Way for Botswana’s Next Era of Diamond Mining

The Karowe Underground Project in Botswana has entered a decisive new phase with the successful completion of the production shaft to its full depth of 770 metres, a milestone that signals Lucara Diamond’s steady advance toward transforming Karowe from an open pit mine into one of the world’s premier underground diamond operations. This achievement arrives after a period of technical difficulty, particularly the severe water inflows experienced in 2022 and 2023, and it marks a renewed sense of momentum under the leadership of returning CEO William Lamb.

With the open pit scheduled to cease operations in the first half of 2026, Lucara plans to rely on existing stockpiles to maintain processing continuity until underground production begins in the first half of 2028. The underground expansion is strategically designed to target only the South Lobe of the AK6 kimberlite, which is globally renowned for its unusually high value and consistent recovery of exceptionally large diamonds. To safely extract the ore body across 400 metres of vertical extent, the mine will employ bulk stoping supported by mass longhole shrinkage, a method chosen for its efficiency and ability to preserve large, high value stones. Once operational, the underground mine is expected to process 2.7 million tonnes of ore each year, generating approximately 450 000 carats annually and contributing to an estimated total recovery of 6.8 million carats over the life of mine. Ventilation shaft sinking is also progressing and is now within 35 metres of its final depth, complemented by plans for eight working levels, with the 310 Level becoming the central infrastructure platform for services, haulage, and distribution.

A defining feature of the project has been its outstanding safety performance. The site has accumulated more than 5.7 million hours and 2 000 days without a Lost Time Injury, a significant benchmark for an underground development of this scale. Much of this success is attributed to the Safe Start behavioural safety programme introduced in 2022, which has strengthened risk awareness and operational discipline during intensive construction activities. The project’s capital cost has risen to 683 million US dollars, primarily due to the extensive engineering and mitigation measures required to address water inflows, and Lucara has now taken direct management control following the termination of the EPCM contract. The preproduction phase will also require 16 kilometres of lateral development, a process supported by advanced geomechanical modelling to optimise stability, sequencing, and long term production reliability.

Karowe’s current performance reinforces its position as one of the world’s most important sources of large, high value diamonds. In 2024, the mine delivered strong operational outcomes, recovering 361 673 carats and maintaining an operating margin of 61 percent. The continued recovery of mega stones, including diamonds exceeding 2 000 carats and the spectacular 2 488 carat Motswedi, showcases the rarity and geological uniqueness of the deposit. Lucara continues to rely on state of the art XRT technology to recover such stones intact, a capability that distinguishes Karowe from most diamond mines globally and underpins its premium market position. With the underground project expected to extend the mine’s life to at least 2040 and maintain low operating costs, the expansion is set to reinforce Botswana’s standing as a global leader in natural diamond production.

Looking ahead, the successful transition to underground mining at Karowe could have far reaching effects on Botswana’s mining sector and Africa’s diamond economy more broadly. By unlocking deeper, higher value resources and sustaining long term production, the project strengthens revenue stability, supports advanced mining skill development, and demonstrates how African producers can integrate modern technologies to enhance competitiveness. If Lucara’s expectations prove correct and stones up to 5 000 carats are eventually recovered, Karowe may further elevate global interest in African diamond geology and contribute to increased investment in high value, technologically intensive mining expansions across the continent.

Mini Glossary

• Bulk stoping: A large scale underground mining method used to extract massive ore bodies efficiently.
• Longhole shrinkage: A technique where drilled ore is blasted and left to accumulate in the stope to support the walls while mining continues upward.
• Kimberlite: A volcanic rock that sometimes contains diamonds and forms the primary source of most mined diamonds.
• XRT technology: X ray Transmission sorting technology that identifies and recovers diamonds by detecting their atomic density.
• EPCM contract: Engineering, Procurement, and Construction Management agreement where a contractor oversees major project components.
• Geomechanics modelling: The analysis of rock mass behaviour to design safe mine structures and extraction sequences.