How Are Diamonds Mined?

diamond engagement rings sitting on a leaf

Although your search for a natural diamond may begin with a trusted online retailer or in a velvet lined glass case, diamonds come from—or are more accurately mined from—a source much closer to earth. About one hundred miles underground, heat and pressure from the earth crystallize carbon into rough diamonds. But how are diamonds mined so that they get from the earth to your ring?

A specific type of volcanic eruption, the kimberlite eruption, brings Kimberlite, a diamond-containing igneous rock, closer to the earth’s surface—with the most recent eruption occurring over 100 million years ago. Kimberlite is commonly found in kimberlite pipes—vertical structures in the earth’s crust. Diamonds are mined from Kimberlite through three types of diamond mining: alluvial mining, pipe mining, and marine mining.

How are diamonds mined? Meet the 3 different methods

Alluvial diamond mining occurs in riverbeds and beaches, where thousands of years of erosion and natural forces such as wind, rain, and water currents wash diamonds from their primary deposits in kimberlite pipes to beaches and riverbeds. Miners build walls or divert rivers to expose the diamond-bearing dry river or ocean bed. While workers initially sifted through the sand at the original site, the process soon advanced, with sand being transported to a screening facility to be more efficiently processed.

As the global demand for diamonds increased, diamond miners developed modern day’s most common form of diamond mining: pipe mining. While alluvial mining requires waiting for diamonds to first rise up through kimberlite pipes and be washed away by erosion to settle on river or ocean beds, pipe mining allows diamond miners to strike closer to the source—the kimberlite pipes. Pipe mining has two forms: open-pit diamond mining and underground diamond mining.

Open-pit diamond mining is used closer to the earth’s surface, as miners remove the layers of sand and rock just above the kimberlite rocks. In contrast, underground mining requires the creation of two parallel and vertically connected tunnels where miners in the top tunnel blast the ore of the kimberlite pipes which falls and collects on the bottom tunnel.

Marine diamond mining

The third method, marine diamond mining, extracts diamonds from the ocean floor. While the earliest form of marine diamond mining laboriously required a swimmer to collect gravel from a shallow seabed, modern technology granted access to greater depths through horizontal and vertical marine mining. Horizontal marine diamond mining uses a crawler to suck gravel from the ocean floor to the surface via flexible pipes, while vertical diamond mining uses a large, ship-mounted drill to pull up the diamond-bearing gravel.

Diamond mine locations

These mining techniques occur in diamond mines all over the world. Diamond mines exist as both privately owned entities and government sponsored enterprises, with some the earliest diamonds found in India in the 4th century BC. Following the decline in Indian diamond mining, diamonds was discovered in Brazil in the 1720s, North America in the 1840s, and in Africa in the 1860s. The rise of African diamond mines sparked the Great Diamond Rush as well as the Kimberly Mine, the first largescale diamond mining operation.

The largest diamond mines

While Africa was once the center of diamond mining, producing upwards of 90 percent of the global diamond supply, Africa now produces less than 50 percent of the world’s diamonds. Data from the 2016 U.S. Geological Survey states that Russia produces the most gem-quality diamonds—housing half of the world’s largest diamond mines— followed by Botswana, Canada, Angola, and South Africa. But the coveted title of “world’s largest diamond mine” can vary.

In 2016, global diamond expert, Ehud Arye Laniado, listed the world’s largest diamond mines (determined by reserve size) as the Orapa diamond mine and Jwaneng diamond mine in Botswana, and the Jubilee diamond mine of Russia. In contrast, diamond expert Paul Zimnisky gave his ranking of the world’s largest diamond mines as the Jwaneng diamond mine, the Jubilee diamond mine, and Russia’s International diamond mine. However, large and commercially viable diamond mines are rare, with only about 20 major diamond mines in existence today.

The Kimberly Process and conflict diamonds

The rarity of large diamond mines, combined with the high value and extreme labor required to mine diamonds means that the diamond mining industry requires extra precautions for safe and ethical diamond mining practices. In order to standardize mining practices and combat the sale of conflict diamonds— diamonds used to fuel civil unrest or wars—the international community established the Kimberley Process in 2000, a no tolerance policy against the use of conflict diamonds. The Kimberley Process, adopted by 74 governments, requires the issuance and authorization of a certificate for each mined rough diamond in order to promote safe and ethical diamond mining practices.

With all this, it is undeniable that diamonds undergo a long journey—from the warm belly of the Earth to hard-working diamond miners, jewelers, and retailers—in order to find their way home to you and your loved one. And if you'd like to know more about With Clarity's policies and our commitment to the Kimberly Process and conflict-free diamonds, you can find out more about them here.