Diamonds
Tanzania holds estimated diamond reserves of 51 million carats and produced approximately 373,000 carats in 2024, ranking as Africa's ninth-largest diamond producer and 11th globally.[4]
Diamonds, alongside gold, have always been the mainstay of Tanzania's mineral production.
The country's diamond sector is anchored by the Williamson mine in Shinyanga, one of the oldest active diamond mines in the world.
Diamonds are classified within Tanzania's mining framework as both a metallic export commodity and an industrial gemstone, with distinct royalty regimes applying to rough versus cut and polished stones.
Diamond Reserves and Resource Base
Tanzania's diamond reserves are estimated at 51 million carats, positioning the country as a globally significant gemstone jurisdiction.[4]
The bulk of these reserves are concentrated at the Williamson mine in Shinyanga, which alone holds an estimated 37 million carats.
The Williamson mine is one of the oldest active diamond mines in the world, providing a long operational track record and established infrastructure.
Diamonds are classified under industrial minerals as a gemstone category, alongside tanzanite (unique to Tanzania), rubies, garnets, and pearls.
Production Performance
In 2024, Tanzania produced approximately 373,000 carats of diamonds.[4]
In the first nine months of 2025, the country produced approximately 284,000 carats of diamonds valued at USD 47.5 million.[5]
These output levels place Tanzania as Africa's ninth-largest diamond producer and the 11th-largest globally.
Diamond production is overwhelmingly concentrated at the Williamson mine, complemented by medium-scale and small-scale operations that also produce colored gemstones.[3]
Tanzania's Position in Global and African Diamond Markets
Tanzania participates in the international diamond trade through the Kimberley Process certification framework, which sources the country's production data.
Diamonds form part of Tanzania's broader mineral export basket, which in 2025 saw the country ranked the 4th most attractive destination for mining investment in Africa, and the 3rd for its mineral potential.[2]
Within the mineral export mix, gold, coal, and copper concentrates account for the largest share, with diamonds and other gemstones representing a specialised high-value segment.[1]
The diamond sector contributes both to foreign exchange earnings and to rural employment in the Shinyanga region and surrounding mining communities.
Mining Structure and Operators
Tanzania hosts eight large-scale mines, six for gold and two for gemstones, alongside medium-scale mines and numerous small-scale mines, primarily producing gold, diamonds, and colored gemstones.[3]
These mines are owned by domestic and foreign companies, as well as joint ventures between the Government and international investors.
Small-scale mining has seen rapid growth in revenue contribution and employs thousands of Tanzanians, particularly in rural areas.
The Williamson mine in Shinyanga remains the single largest diamond producing asset in the country.
Policy Framework
Royalty Regime
Tanzania applies a 6% gross royalty rate on rough diamonds, the same rate that applies to gold (when not sold to BOT or local refineries), metallic minerals, and rough colored gemstones.[6]
A reduced 1% royalty rate applies to cut and polished diamonds, creating a clear fiscal incentive for in-country value addition.[6]
In addition, a 1% clearance and inspection fee applies to all minerals except salt and gold sold to refinery centers.
The Finance Act of 2025 introduced an HIV Response Levy of 0.1% of the gross value of minerals, which applies to diamond output as well.
Mining Act and Local Content
The Mining Act of 2010 reserves gemstone exploration and mining, including diamonds, for Tanzanian citizens or companies wholly owned and controlled by Tanzanian citizens, though it allows up to 50% foreign participation in specific circumstances.
The Mining (Local Content) Regulations introduced in 2018 and amended in 2019 implement the local content provisions of the Mining Act, requiring that indigenous Tanzanian companies be given priority in the procurement of goods and services.
Mining companies are required to prioritize Tanzanian employment, goods, and services where feasible.
Investment Opportunities
The 51 million carats of estimated reserves, combined with the underexplored geology around the Shinyanga diamond belt, present opportunities for greenfield exploration and brownfield expansion of existing operations.[4]
The 1% royalty rate on cut and polished diamonds, against 6% on rough stones, creates a strong fiscal incentive to establish diamond cutting, polishing, and jewellery manufacturing capacity inside Tanzania.[6]
The 50% foreign participation ceiling on gemstone mining opens a structured route for joint ventures with Tanzanian partners, enabling international operators to access reserves while complying with local ownership rules.
Tanzania's 2025 ranking as the 4th most attractive mining destination in Africa, and 3rd for mineral potential, reinforces the country's competitive position for diamond sector capital deployment.[2]
Adjacent opportunities exist in supplying goods and services to large-scale and small-scale diamond operations, in line with local content regulations that prioritise indigenous Tanzanian suppliers.
Last Update: May 2026
References
- https://www.tumemadini.go.tz/media/uploads/annual_reports/2025/11/24/REPORT_PRINT_2025_A3LATEST_compressed.pdf (Guide reference #139)
- https://www.fraserinstitute.org/sites/default/files/2026-02/annual-survey-of-mining-companies-2025.pdf (Guide reference #140)
- https://www.madini.go.tz/media/United_Republic_of_Tanzania_Investor_Guide..pdf (Guide reference #141)
- https://www.mof.go.tz/uploads/documents/en-1757496956-ECONOMIC%20SURVEY%20BOOK,%202024%20SEPT_SENT%20FINAL.pdf (Guide reference #142)
- https://www.bot.go.tz/Publications/Regular/Quarterly%20statistical%20Bulletin/en/2025110513234194.pdf (Guide reference #145)
- https://www.tumemadini.go.tz/pages/mineral-royalties-and-inspection-fees-rates/ (Guide reference #157)
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