Mbuji-Mayi — The Capital of the Congolese Diamond Industry
Mbuji-Mayi — The Capital of the Congolese Diamond Industry
The Kasai-Oriental city built on alluvial diamonds and the headquarters of MIBA
Mbuji-Mayi is a major city in the Democratic Republic of the Congo, capital of the Kasai-Oriental province, and the historical centre of the Congolese diamond industry. The city sits in the heart of one of the world's most productive diamond-bearing regions, with the surrounding alluvial deposits and the kimberlite pipes of the Kasai region having supplied the international market for over a century. Mbuji-Mayi is the headquarters of Société Minière de Bakwanga (MIBA), the parastatal mining company that has historically dominated formal diamond production in the region.
The Kasai diamond region
The Kasai diamond fields were discovered in 1907 by the Belgian colonial administration and have produced steadily for more than a century. The deposits are dominantly alluvial — diamonds eroded from primary kimberlite sources and concentrated in river gravels and ancient stream beds — with the original kimberlite pipes also worked at MIBA's main operations. The geological setting is unusual in that a high proportion of the production is industrial-grade rather than gem-quality diamond, with smaller proportions of cuttable gem stones recovered from the same deposits.
Industrial diamond from Kasai supplied much of the world's industrial demand through the mid-twentieth century, with the Congolese share of global industrial-diamond production peaking at well over half during the colonial period. Mechanisation, synthetic-diamond competition, and the political instability that followed independence in 1960 reduced both the formal production volumes and the country's share of the global market in subsequent decades.
MIBA and formal production
MIBA — Société Minière de Bakwanga — is the parastatal company that operates the main Mbuji-Mayi diamond mines. Formed from the colonial-era Forminière operations and successively restructured under Congolese government ownership, MIBA has historically been one of the largest single diamond producers in the country. Production volumes have fluctuated significantly with operational, financial, and political conditions, with MIBA experiencing periods of substantial output and periods of near-shutdown over the decades.
Artisanal production and Kimberley Process
Beyond the formal MIBA operations, artisanal small-scale mining accounts for a substantial proportion of the diamond production in the Mbuji-Mayi region. Tens of thousands of artisanal miners work the alluvial deposits with hand tools, with the rough flowing through informal trading networks into the formal export channel at Kinshasa. The Democratic Republic of the Congo is a participant in the Kimberley Process Certification Scheme, with all formal diamond exports requiring Kimberley Process certificates. The artisanal sector has been a focus of significant due-diligence and traceability work under the OECD Guidance for Responsible Supply Chains.
The Mbuji-Mayi diamond character
Diamonds from the Mbuji-Mayi region tend toward the smaller sizes and the more included grades, reflecting the alluvial origin and the long transport history of the rough. Larger and cleaner stones are produced periodically — including some notable historic finds — but the bulk of the production is in commercial sizes and qualities. The cuttable proportion of the Kasai output supplies the broader gem-diamond market, with Antwerp, Mumbai, and Surat serving as the principal cutting destinations.