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Alluvial mining | implications for ethical jewelry What are alluvial diamonds?

on November 15, 2023

Alluvial diamonds are diamonds that have been removed over millions of years from their original or primary source, kimberlite, as a result of natural erosion and have been deposited in a new environment such as a riverbed, coastline or ocean floor.

What is placer mining?

Alluvial mining is the search for valuable minerals and geological material in sand or gravel deposits, which have been brought to these environments by the force of water or wind.

Traditionally, it is carried out on the banks of rivers and in coastal areas, taking advantage of the force of water to extract the precious minerals from the surface. There are different techniques used such as sluicing, hydraulic mining and dredging.

Alluvial diamond mining at an industrial level requires a high investment and is governed by strict government regulations, so mining companies must be formalized and comply with all legal regulations.

Almost 10% of rough diamonds in the world market come from industrialized alluvial mining, and up to 14% is the result of informal or small-scale artisanal mining.


What are alluvial deposits and where we find it?

Alluvial deposits are mainly found in the lower areas of rivers, forming deltas and plains, but they can also form at any other point where the riverbed overflows or stops its flow.

These deposits are essentially composed of clay, gravel, sand, silt and organic matter and are characterized by generating very fertile soils.

The largest percentage of tin supply in the world is extracted from alluvial deposits, as well as gold, platinum and precious stones. They can be found on the Atlantic coast of South Africa and Namibia, in certain river waters of Angola, Ivory Coast, Guinea, Ghana, Sierra Leone, Democratic Republic of Congo, Central African Republic, Liberia, Tanzania, Togo, Venezuela, Guyana, South Africa and Brazil. Rough alluvial diamonds were first discovered in South Africa.


The value of alluvial diamonds and gemstones

The marketing price is closely related to the process of mining alluvial diamonds. In the case of informal mining, where there is no foreign capital participation, production is sold directly to local or international markets by smuggling, at a lower cost than in formal mining. There is no payment of taxes or compliance with regulations, so the final price of the product is affected.

Informal mining production costs are considerably lower than industrialized mining, which means that the supply of diamonds and gems is relatively stable and does not experience large price fluctuations. This supposed price stability may vary if the diamond enters the smuggling chain, where prices vary thanks to the spiral of corruption.


Ethical implications

It is estimated that illegal mining accounts for approximately 20% of total gold and diamond production and up to $80 of the world's traded gemstones. Informal alluvial mining not only has harmful consequences for the environment, but is also an activity that often violates the rights of miners with forced and precarious working conditions.

In diamond mining areas in Africa, for example, miners can be paid less than $1 a day and illiteracy and mortality rates can be quite high. The struggle for land rights is also a major ethical conflict surrounding mining, with local communities often being disadvantaged by governments or large industries that make use of geographical areas for mining.

During the process of extracting placer diamonds, as the product of alluvial mining is also known, many sediments and particles are released that silt up river water and contribute to turbidity.

Historically, illegal mining has been linked to the financing of armed conflicts in different regions of the world and gave rise to the concept of blood diamonds. Respected and formal jewelry houses do not work with diamonds from this type of mining. For example, at Albert Hern you can find a wide variety of ethically sourced diamond jewelry, such as:


Alluvial diamond mining curiosities 

In the year 2022 was found in the alluvial diamond mine of Lulo, in Angola, the probably largest pink diamond in the last 300 years. Named Lulo Rose, these 170 carat stone has attracted worldwide attention. 

Only 1 in 10 thousand diamonds that are mined have color, and only 1 in 100 exceed the size of 10.8 carats. 

Alluvial mining of diamonds is similar to that of gold, and in both forms, washing and screening of the precious minerals are used. Angola's mines are among the top 10 diamond producers in the world market. 

The oldest and most traditional way of extracting diamonds is through alluvial mining, which originated centuries ago in India and has spread throughout the different continents, mainly in Africa and in Latin America, in the Brazilian Amazon.

It is currently carried out in two forms, one manual or informal, which is done by miners with shovels and sieves, along the coasts and in riverbeds, sometimes even using their hands directly to do the work. The industrialized form of alluvial mining uses heavy equipment and tons of sand are collected from the coast and riverbeds.

In the sedimentary alluvial deposits are found rubies, diamonds that are highly valued for their beauty and particular color. The Rosser Reeves Ruby is the largest ruby found and weighs 138.7. It was found in Sri Lanka in 1965.

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