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Cleaning diamonds from the ocean

Beneath sparkling African waters divers explore the seabed with sophisticated detection equipment. Farther offshore, at depths of up to 400 feet, a small fleet of specialized ships deploy crawlers to the ocean floor.

Hidden treasure

For countless ages a steady stream of rough diamonds tumbled down the Orange and Vaal Rivers to the sea, washed there from inland volcanic pipes. Distributed far and wide along the coast by tidal activity, millions of carats now lie hidden in the sediment under the territorial waters of Namibia.

Mining specialist DeBeers’ began working off Namibia in 1991. Thirteen years later the Namibian Government and DeBeers’ entered an agreement to share recovery of coastal diamonds: Debmarine Namibia (DBMN), established in 2004, is owned by the Government of Namibia and DeBeers’ in equal shares.

After 10 years of successful cooperation the Government of Namibia and DeBeers’ announced a further agreement to cooperate in the sorting, valuing and sales of all production from Namdeb and Debmarine Namibia through 2025. Cutting and polishing has also been brought into Namibia, providing additional jobs for many Namibian nationals.

These joint initiatives have resulted in tremendous infrastructure improvement and development for the country. The population is better educated, healthier, and wealthier since being able to benefit from the rich resources hidden just offshore.


Mining, Forestry and Agricultural operations all have environmental impact. For this reason the Namibian Ministry of Fishing and Marine Activity was consulted and included in Debmarine Namibia’s planning starting in 2005. The operation maintains ISO environmental compliance (ISO 14001:2004) and facilitates rehabilitation of mined areas.

There are no major fish spawning grounds and no commercial fishing in the mining area. Dredging equipment was designed so that stray marine life sucked into the pipe is returned to the sea alive. Unlike deep-sea dredging, shallow mining returns tailings to their original beds.

Image credit: DeBeers

Monitoring is performed to facilitate rehabilitation of mined areas, including benthic sampling in cooperation with the country’s Marine Ministry. This can be compared to forestry industry rehabilitation, but it takes only 3-10 years for mined marine areas to rehab.


The mining-lease covers a total of 2,316 sq miles off the Namibian coast. Since operations commenced less than 3% of the area has been mined – approximately 50 square miles in total. Experts say the diamond field also stretches inland, with millions of carats of valuable diamonds buried along the coast. There is not currently a recovery initiative for those areas, as any extraction plan will require extensive planning and significant capital.


In 2018 approximately 1.4 million carats of gem-quality diamond rough were recovered by DBMN. All told, this represented around 75% of all diamond exports from Namibia.

Photo credit: Professional Jeweller

Water softening

Our planet’s supply of natural diamonds are estimated to be 1-3 billions years old. “Primary deposits” are those which remain in volcanic pipes. “Secondary” deposits, also called alluvial, are those removed from their pipes by water and erosion and scattered across adjacent landscapes over the eons.

Logically, rough which was tossed, tumbled and pummeled by nature for millions of years tends to have edges which are more rounded than the sharp edges of rough that remained sheltered in their pipes.

Photo credit: Pollard Professional LLC

Ultimately, rough diamonds from the ocean are no different than their sister crystals from volcanos. They just had a trip to the beach. And, like many of us after a trip to the beach, they became less hard-edged.

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