The Journey of a Diamond: From Diamond Mining to Market Through Extraction and Processing Stages

The journey of a diamond is a fascinating and complex process that spans from the depths of the Earth to the glittering jewelries we adore. Here’s a detailed look at the journey of a diamond, from diamond mining to market, through the various extraction and processing stages.

Diamond Mining: The Beginning of the Journey

Diamond mining is the initial stage in the journey of a diamond. There are several methods of diamond mining, each with its unique characteristics.

Pipe Mining: Primary Deposits

Pipe mining is one of the most common methods and involves extracting diamonds from kimberlite pipes, which are volcanic pipes that bring diamonds to the Earth’s surface. There are two main types of pipe mining: open-pit mining and underground mining.

In open-pit mining, the layers of sand and rock above the kimberlite pipe are removed, and the ore is blasted apart. The broken ore is then loaded into haul trucks and transported to a primary crusher for processing. The Kimberley Big Hole in South Africa is a famous example of open-pit mining.

Underground mining involves tunneling through the Earth’s crust to reach the kimberlite pipe. Miners construct two tunnels, one above the other, with funnels connecting them. Ore is blasted in the top tunnel, falls through the funnels, and is collected in the lower tunnel before being brought to the surface for processing.

Alluvial Mining: Secondary Deposits

Alluvial mining targets diamonds that have been eroded from kimberlite pipes and carried away by rivers and streams. These diamonds are found in gravel layers, often under layers of mud, clay, and underwater plant life. Miners build walls to collect water in one area, isolate the gravel, and then haul it to the surface for processing.

Marine Mining

Marine mining is a form of alluvial mining that takes place on the ocean floor. This method involves using ships with specialized technology, such as crawlers or drills, to collect diamond-bearing gravel from the seabed.

Processing of Ore to Extract Rough Diamonds

Once the diamond-bearing ore and gravel are collected, they undergo several processing stages to extract the rough diamonds.

Stage 1 – Crushing

The first stage involves transporting the ore to a primary crusher, which reduces the size of the ore into smaller pieces, typically no larger than 150mm. A secondary crusher, known as a roll-crusher, may be used to further reduce the size of the ore.

Stage 2 – Scrubbing

In this stage, the crushed ore is scrubbed to remove loose excess material and then screened. Any material smaller than 1.5mm is discarded as it is too costly to extract diamonds from such small pieces.

Stage 3 – Cyclonic Separation Plant

The ore is mixed with a solution of ferrosilicon powder and water, which is fed into a cyclone. The cyclone tumbles the material, forcing a separation where materials with high density, such as diamonds, sink to the bottom.

Stage 4 – Recovery

The diamond-rich concentrate from the cyclonic separation plant goes through several processes, including magnetic susceptibility, X-ray luminescence, and crystallographic laser fluorescence. These processes are designed to separate the rough diamonds from other heavy density materials. Sensors detect the unique properties of diamonds, such as their fluorescence when exposed to X-rays, and use this information to collect the diamonds.

Stage 5 – Cleaned, Weighed, and Packaged

The collected diamonds are cleaned in an acid solution, washed, weighed, and packaged in sealed containers. These containers are sealed with tamper-resistant seals, numbered on site, and a certificate of origin is issued in accordance with the Kimberley Process.

From Rough Diamonds to Market

After the diamonds are extracted and processed, they are sorted, classified, and valued based on their size, shape, quality, and color. Gem-quality diamonds are then distributed to cutting and trading centers around the world, such as Antwerp, Mumbai, Tel Aviv, New York, and Johannesburg.

Cutting and Polishing

The rough diamonds undergo meticulous cutting and polishing processes. Cutters use techniques such as cleaving, sawing, or laser cutting to separate the rough into smaller pieces. The girdler then uses a process called bruting to grind away the edges and provide the outline shape. Faceting follows, where the blocker cuts and polishes the initial facets, and the brillianteer cuts and polishes the final facets to create the brilliant gem.

Final Preparation and Market

Once polished, the diamonds are boiled in acids to remove dust and oil. They are then sold and traded in registered diamond bourses around the world. Finally, these polished diamonds are set into finished pieces of jewelry by manufacturers, ready to be cherished by their new owners.

The journey of a diamond, from diamond mining to market, is a remarkable tale of transformation from a rough stone deep in the Earth to a sparkling gem adorning our lives.