Diamond Mining Under the Sea: What Is Happening to Our Ocean Floor
Part of the True Cost of Mined Diamonds series | Ethica Diamonds, Newquay, Cornwall
We are based in Newquay, Cornwall. The sea is part of our daily life here - the sound of it, the smell of it, the way it changes colour with the light and the season. We feel its health as something personal.
So when we started researching undersea diamond mining, it did not feel abstract. It felt urgent.
Here is what is happening beneath the surface of the ocean, in the name of diamonds.
Why Mining Companies Turned to the Sea
For most of diamond mining's history, the industry focused on land. Kimberlite deposits deep underground, open pit mines, alluvial operations in riverbeds and floodplains. But those deposits are finite, and many of the most productive land-based mines in Canada, Russia, and southern Africa are reaching the end of their commercially viable lives.
So the industry began looking elsewhere. And it found that the sea had something to offer.
Over hundreds of thousands of years, rivers flowing through diamond-rich territories have carried stones from their inland sources out to sea, depositing them in the sediment of the ocean floor near river mouths. The Orange River, which marks the border between Namibia and South Africa, is one of the most significant of these - and the seabed off the Namibian coast has become the frontier of a new kind of diamond mining.
The diamonds found here are of exceptional quality. The journey downriver destroys weaker, more flawed stones. What survives and settles on the seabed is the best of what the land produced - large, high quality gems buried in a relatively shallow layer of sediment, just miles from the shore.
For diamond companies, it is an enormously attractive prospect.
How It Works
Undersea diamond mining is not like anything most people imagine when they think about mining. There are no miners in hard hats. There are no drilling rigs visible from the shore. The operation is almost entirely automated, and it takes place out of sight beneath the waves.
The process begins with detailed scanning of the seabed to map the topography and identify the most diamond-rich areas. Samples are extracted and analysed. Then the extraction begins.
The primary tool is a crawler - a large submersible vehicle that travels along the seabed on tracks, connected to a processing ship above by an enormous umbilical pipe. The crawler moves across the seabed, dredging up the top layer of sediment using suction and, where material is more compacted, high pressure water jets. Everything within reach is sucked up - sediment, rocks, marine life, and diamonds together - at rates of up to 60 tonnes per hour, pumped up through the pipe to the ship above.
On the ship, the material is washed, crushed, and filtered. Diamonds are isolated and sealed into containers. The remaining sediment is discharged back into the sea.
De Beers named their best new mining vessel the SS Nujoma. Their own internal nickname for it was the Butcher. That tells you something about what they knew they were doing.
De Beers and the Namibian Government
De Beers leads this industry through Debmarine, a 50-50 joint venture with the Namibian government. In 2015 alone, Debmarine mined 150 million carats of diamonds off the Namibian coast. De Beers has signed a 50-year agreement with the Namibian government to continue this operation - five decades of systematic extraction from a seabed ecosystem we barely understand.
So far, mining has covered approximately 2% of the licensed area. 27% of the total licensed zone has been found to contain diamonds. There is, by their own assessment, a great deal more to take.
De Beers has attempted to market these marine diamonds as being more environmentally friendly than land-mined diamonds. The argument goes that the seabed is less ecologically significant than land habitats, and that sediment is returned after processing.
Scientists, marine biologists, and environmental organisations strongly disagree.
What We Do Not Know - and Why That Is the Problem
The honest truth about the deep ocean is that we know remarkably little about it. Between 85 and 95% of the ocean floor has never been mapped in detail. New species are discovered regularly. Behaviours and ecological relationships that have taken millions of years to evolve are still being described for the first time.
A project called Seabed 2030 was launched to map the entire ocean floor. At the time of writing, between 5 and 15% has been mapped - primarily in major shipping lanes and coastal waters, largely excluding the deep ocean. The ambition is to complete the mapping by 2030. The Debmarine operation has been running for years already.
In other words: we are systematically extracting from an environment that we have not yet fully described. We are mining ecosystems that we have not yet catalogued. And we are doing so under a 50-year agreement, with no reliable baseline against which to measure the damage.
It is not possible to assess the environmental impact of an activity on an ecosystem you do not understand. Marine diamond mining is proceeding faster than the science that might tell us what we are destroying.
What the Sediment Return Does Not Fix
De Beers points to the fact that processed sediment is returned to the seabed as evidence of environmental responsibility. This deserves examination.
The sediment that is returned is not the same as the sediment that was removed. It has been crushed, washed, and filtered through industrial processing. The microscopic organisms that lived within it - the plankton, the bacteria, the tiny invertebrates at the base of the marine food chain - do not survive the process. The organic material that gave the sediment its ecological function has been destroyed.
Returning processed sediment to the seabed is not restoration. It is returning an inert substrate to a place where a living ecosystem used to be.
Recovery timescales are entirely unknown. No mining operation has been running long enough to provide long term data. The 50-year agreement means that by the time any meaningful recovery data might exist, the mining will have moved on to new areas.
The Protected Coast and the Unprotected One
Here is a detail that stops us every time we think about it.
The entire northern coastline of Namibia - the Skeleton Coast - is protected by a vast national park. The southern half of the coast also has national park status, with 25% of the coastline protected to a distance of 30 kilometres seaward. Work is even underway to have the entire Namibian coast designated a World Heritage Site, in recognition of its extraordinary wildlife and ecology.
The area being mined - the river outfall zone where the Orange River meets the sea - sits just outside these protected areas. The ecosystems on either side of the mining zone are considered significant enough for the highest levels of international protection. The mining zone itself is not.
The logic that makes this possible is exactly the same logic that has governed diamond mining on land for over a century: the economic value of the diamonds outweighs the ecological value of what surrounds them. Protect what you must. Extract what you can.
The Wider Picture
Namibia is not the only area being considered. Diamond deposits may exist in the Indian Ocean and in the Clarion-Clipperton Fracture Zone, a deep-sea region between Hawaii and Mexico. These areas are even less explored and even less understood than the Namibian seabed.
As land-based diamond deposits continue to decline, the pressure to find and exploit marine deposits will only increase. The Namibian operation is the proof of concept that makes every other potential marine mining site more commercially attractive.
Scientists have expressed grave concerns about the precedent being set. Once the infrastructure is established and the commercial case is proven, the argument for leaving other marine environments intact becomes harder to make - particularly in countries where diamond revenues represent a significant proportion of national income and where environmental regulation may be shaped by the same interests that benefit from mining.
Why This Matters to Us in Cornwall
We make jewellery by the sea. We care about the ocean in a way that is not abstract or theoretical - it is the place we walk, the thing we look at, the environment we live alongside every day.
The ocean produces more than half of the world's oxygen. It regulates the climate. It sustains billions of people. It contains ecosystems of extraordinary complexity and beauty, most of which we have never seen and many of which we have not yet named.
The idea that we should mine it for diamonds - luxury goods, bought at premium prices in wealthy countries - while we still do not know what we are destroying, troubles us deeply.
This is one of the reasons we exist. Not the only one, but a significant one.
The Alternative
A lab grown diamond is created in a laboratory. No seabed is disturbed in its production. No crawler moves across the ocean floor. No sediment is processed through industrial machinery. No marine ecosystem is stripped bare so that the remains can be discharged back into the water.
The stone is the same. Chemically identical, physically identical, optically identical. Independently certified by the GIA or IGI. Set in recycled precious metals. Grown using renewable energy.
At Ethica Diamonds in Newquay, this is what we sell. Because we think that what is under the sea is worth more than what can be extracted from it.
Read the Full Series
The True Cost of Mined Diamonds: What Happens to the Land →
The True Cost of Mined Diamonds: What Happens to the Water →
The True Cost of Mined Diamonds: What Happens to the Wildlife →
The True Cost of Mined Diamonds: The Human Cost, Part 1 →
The True Cost of Mined Diamonds: The Human Cost, Part 2 →
Choose a lab grown diamond from Ethica →
Browse our full collection of lab grown diamond engagement rings at ethicadiamonds.com, or book a free consultation with our team in Newquay - in person or virtually from anywhere in the UK.
