Marange is an alluvial and conglomerate-hosted diamond field in Manicaland Province, eastern Zimbabwe, lying near the Mozambican border around the Save and Odzi river drainages. The deposit was made public in 2006 after informal diggers swarmed onto a concession previously held by African Consolidated Resources, prompting one of the largest unregulated diamond rushes of the modern era. Within a few years the field was producing on a scale comparable to the world’s largest mines, and the name Marange entered the trade as both a geological reference and a political flashpoint.

Geologically the diamonds occur in a Cretaceous to Cenozoic conglomerate cap and in derived alluvial gravels rather than in fresh kimberlite pipes. Source rocks are not yet conclusively identified within Marange itself, leading geologists to posit either older eroded kimberlitic feeders or longer-distance transport from the Limpopo Belt. The diamonds are typically small to medium in size, often coated, with a high proportion of industrial and near-gem quality material; gem-quality stones occur but the run-of-mine assortment skews to the lower colours and more included goods.

The field’s chief significance to the international trade lies in its sheer volume rather than its quality. At peak the operating joint ventures – principally Mbada, Marange Resources, Anjin and Diamond Mining Corporation – collectively contributed a meaningful share of global rough by carat weight. After consolidation in 2016 the Zimbabwe Consolidated Diamond Company was formed to centralise production under state control.

Marange’s reputation in trade circles is inseparable from the human-rights questions that attached to it from the start, and which continue to shape Kimberley Process debates today. For working gemmologists the practical issue is provenance: stones traceable to Marange face heightened scrutiny in many jurisdictions, and reputable houses generally insist on a documented chain of custody before purchasing rough or polished goods understood to come from the field.