Diamonds, recognized as the hardest natural material on Earth, are a crystalline form of carbon. These remarkable gems originate deep within the Earth’s mantle under conditions of extreme heat and pressure, typically at depths exceeding 120 kilometers (75 miles) and temperatures between 900°C and 1300°C. Over millions to billions of years, carbon atoms bond in a unique cubic crystal lattice structure to form diamonds.
Global Distribution of Diamond Deposits
Major diamond-producing nations are distributed across several continents, with Russia consistently leading in terms of carat volume. Russia’s diamond resources are concentrated primarily in the Siberian region of Yakutia, where large open-pit mines like Aikhal operate. ALROSA, a partially state-owned company, produces a significant portion of Russia’s output, contributing to its status as the world’s largest exporter of rough diamonds by volume.
Botswana stands as another significant global producer, particularly noted for the high value of its diamonds, and ranks second in terms of volume. Mines such as Jwaneng, often considered the richest diamond mine by value, play a substantial role in the country’s economy. Other key players in Africa include Angola, known for its larger than average sized diamonds, and South Africa, home to the Venetia mine.
Beyond Africa, Canada has emerged as a prominent producer, with significant discoveries in its northern regions. Australia, while also a major producer, is particularly recognized for its colored diamonds, including rare pink and red varieties, largely from the Argyle mine. The Democratic Republic of Congo also contributes a notable volume to the global diamond supply.
Primary Geological Settings
Diamonds are primarily found in two main geological settings: primary deposits within specific volcanic rock formations and secondary deposits formed by erosion and transportation. The most common primary sources are kimberlite pipes, which are carrot-shaped, vertical structures formed by explosive volcanic eruptions. These eruptions rapidly carry diamonds from the deep mantle to the Earth’s surface.
Lamproites, like kimberlites, are igneous bodies that transport diamonds from great depths. Both are found in ancient, stable continental regions known as cratons. While thousands of these pipes exist globally, only a small fraction contain diamonds in economically viable quantities.
Secondary deposits, also known as alluvial deposits, form when diamonds are eroded from their primary kimberlite or lamproite sources and transported by natural forces. Rivers, streams, and even glaciers can carry these diamonds, redepositing them in riverbeds, coastlines, or floodplains. Historically, many early diamond discoveries, including those in India and Brazil, originated from these alluvial sources.
Public Access Diamond Mining
Crater of Diamonds State Park in Murfreesboro, Arkansas, USA, offers a unique opportunity for public diamond prospecting. This park, an eroded lamproite volcanic pipe, is the only diamond-producing site in the world open to the public where visitors can search and keep any diamonds they find. The 37.5-acre plowed field at the park allows visitors to sift through the earth for diamonds and other gemstones.
Since its establishment as a state park in 1972, over 75,000 diamonds have been discovered by visitors. Notable finds include the 40.23-carat “Uncle Sam” diamond, the largest diamond ever found in the United States. While the odds of finding a large diamond are low, park staff report that one or two diamonds are typically found daily by visitors. Visitors can rent tools on-site or bring their own equipment, and park staff are available to identify and certify any stones found.
Ensuring Ethical Sourcing
Ethical sourcing is an important consideration for diamonds. The Kimberley Process Certification Scheme (KPCS), established in 2003, prevents the trade of “conflict diamonds”—rough diamonds used to fund armed conflicts.
It requires participating countries to certify rough diamond shipments as “conflict-free,” increasing transparency and oversight. The scheme involves strict requirements for members, including national legislation, export and import controls, and data exchange. Other initiatives, such as the Responsible Jewellery Council (RJC) and the World Diamond Council (WDC), promote broader ethical standards, including environmental sustainability and fair labor practices.