Diamonds are a crystalline form of pure carbon, known for their unmatched hardness and brilliant luster. Their extraordinary properties result from formation under extreme conditions deep within the planet. The story of every diamond begins with its geological creation and culminates in its geographical discovery, revealing the intense forces that shape the Earth and the specific locations where these natural treasures are brought to the surface.
The Deep Earth Recipe
The creation of a natural diamond requires specific environmental parameters found only far beneath the Earth’s surface. Carbon atoms must be subjected to immense pressure and extremely high temperatures to force them into the dense, tetrahedral lattice structure that defines the gemstone. These conditions are found within the lithospheric mantle, a rigid layer of the Earth’s interior extending hundreds of kilometers down.
The necessary pressure ranges from 4.5 to 6 gigapascals, which is more than 45,000 times the atmospheric pressure at sea level. Simultaneously, temperatures must hover between 900 and 1,300 degrees Celsius, providing the energy needed for the carbon atoms to reorganize. This stable environment for diamond growth, known as the diamond stability field, exists at depths between 120 and 210 kilometers underground. These conditions are usually found beneath the oldest and most stable parts of continental crust called cratons.
Transport to the Surface
Although the mantle is the birthplace of diamonds, they are brought to the surface through rare, deep-source volcanic eruptions that punch through the crust. These eruptions create vertical, cone-shaped rock formations called pipes, rather than typical surface volcanoes.
The primary conduit for this transport is kimberlite rock, and less commonly, lamproite. These magmas originate at the same depths as the diamonds and ascend rapidly, carrying fragments of the mantle rock. Rapid ascent is crucial because a slow rise would allow the diamonds to revert to graphite. This explosive, gas-rich volcanism creates a carrot-shaped column that solidifies near the surface, trapping the diamonds within the host rock.
Global Mining and Sourcing
The final stage of the diamond journey involves recovery from two distinct types of geological deposits.
Primary Deposits
Primary deposits are where diamonds remain embedded within the original kimberlite or lamproite pipe rock, requiring hard rock mining methods. These pipes are found almost exclusively on ancient continental cratons underlying parts of Africa, Russia, Canada, and Australia.
Secondary Deposits
Secondary or alluvial deposits form when primary source pipes are eroded over millions of years, and the liberated diamonds are washed away. These diamonds are carried by rivers, glaciers, or ocean currents, accumulating in riverbeds, lake bottoms, or offshore marine environments. This type of deposit requires less capital-intensive mining techniques, such as dredging or sifting through gravel.
The vast majority of global diamond production is concentrated in a few nations.
Russia currently leads the world by volume, with major mining operations centered in the Siberian region of Yakutia. Botswana is consistently ranked as one of the world’s largest producers by value, known for its high-quality gem-grade stones.
Canada has emerged as a significant producer in recent decades, with mines located in the remote Northwest Territories and northern Quebec. Australia, historically known for the now-closed Argyle mine which produced rare pink diamonds, still contributes to the global supply.
Other notable producers include South Africa, the historical birthplace of large-scale diamond mining. The Democratic Republic of the Congo also contributes, often relying on smaller-scale artisanal mining operations.