Diamond Mining

               Of all the diamonds mined in the world each year, less than half are gem quality; the rest fall into two other main categories known as near-gem quality and industrial quality diamonds.
Gem quality diamonds display a high standard of excellence in quality and are used in diamond rings and other diamond jewelry. The clarity of these loose diamonds ranges from flawless through to visible inclusions.
Near-gem quality diamonds represent those stones of a quality between gem and industrial that in fact can be used as either depending on the individual stone. These stones have clarity grades ranging from visible inclusions through to industrial.
Industrial quality diamonds are low quality or badly included stones and are suitable only for industrial use; for example, they are used in dentist's drills and earth moving equipment.

Diamonds are recovered by way of pipe or alluvial mining.

Pipe Mining

Pipe mining refers to the extraction of diamonds from volcanic pipes. Typically, a very large area has to be covered. An average of 250 tons of ore must be mined in order to produce a one-carat gem quality polished diamond.

In most countries, a diamond pipe mine is composed of kimberlite, or blue ground. Initially kimberlite is dug from the surface of the pipes in rough opencast mining. Once the surface deposits have been exhausted, shafts are sunk into the ground at the edge of the pipes, and tunnels are driven into the deeper parts of the pipes.

Open Cut Mining

In open cut mining, the ore is dislodged by blasting and then loaded by excavators into 120-ton dump trucks. The ore is then transported to the processing plant where the diamonds are extracted. The processing techniques are purely physical and involve crushing, scrubbing, screening and gravity separation of the diamond-bearing ore. Final diamond recovery is achieved by the use of x-ray sorting machines. The machines can detect and remove diamond material because the diamonds fluoresce under x-ray. 

Top 10 Diamond Mines

1. Russia: Mirna Mine is the largest diamond deposit in Russia and one of the largest in the world.
2. Australia: Argyle Diamond Mine is the largest producer in world, mostly industrial grade. Rio Tinto.
3. Botswana: Jwaneng Diamond Mine produces small stonesand is the richest mine in world.
4. Angola: Fourth largest diamond mine in world. Kimberlite pipe.
5. Angola: Catoca Diamond Mine: Luzamba Diamond Mine is Angola’s largest alluvial mine, Endiama (50%), Odebrecht (50%).
6. Botswana: Letlhakane Diamond Mine: (“little reeds”) second oldest of four – De Beers mines in Botswana.
7. Botswana: Orapa Diamond Mine near a resting place for lions is the largest and oldest of the four DeBeers mines in Botswana.
8. Congo: Bakwanga Mine are alluvial river mines in Kasaï. MIBA.
9. Sierra Leone: Magna Egoli Mine is the largest mechanized mine in Sierra Leone.
10. South Africa: Cullinan Diamond Mine is a open pit and hard rock diamond mine owned by De Beers.

How diamonds are found: exploration

For centuries the exquisite beauty and inner fire of diamonds have made them prized above all other gems, and each diamond is endowed with a character uniquely its own.


Generally, kimberlites occur in clusters of up to five or more, in close proximity to each other. They are not necessarily all the consequence of a single volcanic event. Indeed, they may have resulted from several different events over a period of time, adding to the complexity of sampling and proving their economic potential.
Geologists use many methods to explore for kimberlites, including satellite remote sensing, geophysics and reconnaissance sampling. Any kimberlites discovered can then be drilled to establish whether or not they contain economic quantities of diamonds.
The first step is generally to investigate areas with a history of diamond recovery, and then to follow up with stream or deflation sampling for evidence of kimberlite indicators such as garnets. Thereafter, the use of geophysics to search for magnetic anomalies is applied. Sampling and drilling are then used to confirm whether the anomalies are indeed kimberlites.
Once an anomaly has been confirmed as a kimberlite, HMA sampling of representative material is carried out as a quick and efficient method of assessing whether the kimberlite has the potential to be diamondiferous. Micro-diamond and mini-bulk sampling are then used to establish if there is the potential for those kimberlites prioritised by HMA sampling to host an economic concentration of diamonds.
If positive results are achieved through the initial processes mentioned above, then a company will be in a position to commence bulk sampling material by drilling the deposit and extracting core for analysis. The aim is here to establish the economics for mining a particular kimberlite, and will give indications of grade, cost per tonne and average value per carat. From here, a production decision can be made.