The Lifecycle of A Diamond: From Mining To Setting

diamond lifecycle
Worthy Staff

By Worthy Staff | Apr 4th, 2022

Have you ever thought about where your diamond comes from or how it got to you? Have you ever wondered how old your diamond might be? The lifecycle of a diamond began millions of years ago and your stone will have gone through many different stages and cycles to make it’s way into your jewelry box. 

In this 2 part series, we explore the lifecycle of a diamond and how that impacts the environment. We also look at ways to curb this impact by making smart choices when it comes to your diamond. 

How Are Diamonds Formed?

Diamonds are created deep within the Earth, in an area around 100 miles under the Earth’s surface known as the upper mantle. The carbon that exists there is under a tremendous amount of pressure from all of the material above it and the temperatures are very hot. The carbon atoms bond together to form crystals that come together in the form of diamonds. 

The diamonds we see today were actually formed millions of years ago and brought up in volcanic eruptions. These eruptions, which also took place millions of years ago, brought up material from deep within the Earth through violent, quick eruptions. The eruptions carried the already formed diamonds to the surface by emitting volcanic material or magma. When the magma cooled, it turned into a type of rock known as Kimberlite and the diamonds remained contained within that rock. You can learn more about these eruptions and how diamonds are formed in Smithsonian Magazine. The chasms through which the eruption took place are now known as Kimberlite pipes and many of today’s diamond mines are located around these pipes. 

Where Are Diamonds Mined?

There are diamonds mines all over the world but the biggest diamond-producing countries are Russia, Canada, Botswana, Australia, the Democratic Republic of Congo, and South Africa. Russia is currently the largest producer of gem-quality diamonds. In 2021, a total of 111 million carats were mined globally, a number that’s been declining since 2018 both because of COVID-19 and depleted diamond reserves. 

How Are Diamonds Mined?

Diamonds can be found in a few different areas and that determines the type of mine. Diamonds can be found suspended in Kimberlite ore which sits just under the surface of the earth. The Kimberlite ore is broken down or extracted to get closer to the diamonds. Another way diamonds can reach us is in bodies of water. Over time, Kimberlite pipes have become eroded by natural causes and pieces break off in streams and rivers, carrying the diamond-bearing ore to the bottom of the sea or a riverbed. Once again, the larger pieces of ore need to be extracted so that they can be sorted through for diamonds. 

What Are The Types of Diamond Mines?

There are four types of diamond mines and the type of mine used depends on how miners can access the ore. 

Open-Pit Mining

In an open-pit mine, the top layer of the Earth’s surface is removed to expose Kimberlite ore. Once the Kimberlite is exposed, the ore is blasted apart into large chunks and transported to processing sites that break the ore down further to find the diamonds within.

Underground Mining

Underground mines tunnel into the Earth to reach the Kimberlite pipes rather than exposing the ore from the surface. Miners create two tunnels stacked on top of each other, with holes connecting the two. In the top tunnel, miners blast apart the Kimberlite ore and the large pieces tumble down into the second tunnel, where they are collected and brought up to the surface for processing.

Alluvial Mining

Alluvial mining mines the gravel found at the bottom of a body of water rather than in large pieces of ore. The diamonds found in alluvial mining have been broken off from an eroded Kimberlite pipe and carried by water to beaches and riverbeds. When areas of water are found, miners block off the area with sea walls and dams to isolate the area where they remove the mud, clay, and underwater plant life to reach the layer where the diamond-bearing gravel lays. 

Marine Mining

Marine mining is similar to alluvial mining in that it is mining gravel and sediment in bodies of water. However, marine mining takes place in the ocean on the seafloor. Earlier forms of marine mining had divers going out to sea to collect gravel containing diamonds and bringing back to land. Today, this process is done by ships in two ways. Horizontal mining sends a large crawler across the seafloor to suck up diamond-bearing gravel and bring it up to the ship. Vertical mining uses a large drill mounted to a ship to pull up the diamond-bearing gravel.

How Are Diamonds Extracted?

Once the pieces of diamond-bearing have arrived at the processing site, it goes through 5 stages to extract the rough diamonds from the rest of the materials. 

Stage 1: Crushing 

The pieces of ore and gravel are put through a crusher, which breaks the rock down into smaller pieces (about 150 mm or smaller) to make them more manageable. In some cases, a smaller crusher is used to break down the rocks even further. 

Stage 2: Scrubbing

The smaller pieces of rock are now scrubbed to remove any excess materials that can easily come off. The rocks are then screened and measured, removing any pieces smaller than 1.5 mm. The diamonds that may be contained within these pieces of ore are too small to be worth the price of extracting them. 

Stage 3: Cyclonic Separation

The small pieces of ore are mixed with water and ferrosilicon powder, which helps separate the metals in the ore. The mixture is then put into a cyclone where it is tumbled around and forced to separate. Heavier materials (like diamonds) drift to the bottom while lighter materials are sucked up at the top. The materials left at the bottom should be full of diamonds.

Stage 4: Recovering the Diamonds

The materials are then moved through a few different processes to locate the diamonds still hidden in ore from other pieces of ore that are heavy but don’t include a diamond. These processes include magnetic susceptibility, x-ray luminescence, and crystallographic laser fluorescence. As they are being processed, the diamond within the ore emits flashes of light which sensors pick up and send the diamonds into a collection box.

Stage 5: Cleaned, Weighed, and Packaged

The rough diamonds are then cleaned in an acid solution before being washed, weighed, and packaged for transportation. 

Now the diamonds are ready to be cut and polished. Looking at the lifecycle in terms of the diamond market, the diamonds are now sold by mining companies to cutting and polishing companies. This means that the rough diamonds need to be shipped to the cutting and polishing centers which are located in India, Belgium, the UAE, Israel, the US, and Hong Kong. 

Cutting and Polishing Rough Diamonds

Transforming a diamond from its rough form into the glittering gemstone you have in your jewelry box is a task left to the experts. It involves precision and technology to make sure the diamond is cut perfectly and the reason for this is that the way in which a diamond is cut affects the appearance of the diamond which in turn affects its value. Here is the 5-step process a diamond undergoes: 

Analyzing

When the rough diamond arrives in the hands of a diamond cutter, that expert needs to perform an in-depth analysis to understand the best way to cut the diamond. A diamond cutter is a highly trained professional who considers the size, shape, clarity, and crystal direction of the diamond within the rough stone. 

Marking

The diamond cutter uses a 3D laser to mark where they want to cut the diamond. This needs to be very exact as any error, even by a fraction of a millisecond, can have a major impact on the diamond’s quality and price. If the diamond has an inclusion, it is up to the diamond cutter to determine if the diamond should be cut into one large stone with an inclusion or to work around the inclusion to create a few smaller but higher-quality stones. 

Sawing

As diamonds are the hardest substance on Earth, they can only but cut by another diamond. Diamond cutters use a copper blade coated in diamond dust to cut through the diamond. Again, the diamond cutter needs to be very precise when cutting to ensure a quality diamond is produced. 

Blocking

The sawing produces the diamond basic shape and from here the stone moves on to the blocking step which is where the facets of the diamond are created. There are two phases of blocking – in the first, the blocking establishes the diamond’s basic symmetry by creating 17-18 facets. Smaller diamonds are usually considered finished at this point but for larger diamonds, there is a second phase of blocking to create further facets. Ultimately, it will be the facets that contribute to the diamond’s fire and brilliance. 

Polishing

This is the final step of the process, wherein the diamond’s final facets are polished and shaped. At this stage, diamond professionals are looking to create ideal proportions and perfect symmetry so that the diamond reflects the maximum amount of white light. 

Now the diamond is in its final form and ready to be shipped off to the jewelers and diamond professionals to be sold or set into jewelry. 

In our next article, we explore how the diamond lifecycle, from mining to polishing, impacts the environment and how you can help lessen that impact. 

Sources:

Environmental Impacts of Mined Diamonds, Imperial College London

Diamonds Unearthed

How Diamonds Are Mined

Diamond Cutting & Polishing

Bain & Company Global Diamond Industry Report for 2020-21

Worthy Staff

Worthy Staff


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