You may know your stuff when it comes to the polished loose diamonds and how they’re graded, but how much do you know about rough diamonds and how they’re mined? If you’re like most people, probably not much. People often talk about how the price of a diamond is based on a false sense of rarity, and how the myth of that rarity helps to inflate the value of diamonds. However, it’s a little bit more complicated than that. While diamonds are not as rare as they once were, we never know when a mine may be tapped dry, and when another mine will be found. Plus, once we do find a new diamond mine, there’s no way of knowing – until we start digging – exactly how many stones the mine will yield. And finally, when a mine doesn’t yield many diamonds, there are tens of thousands of tons of dirt that have to be sieved either way. If you want to know more about the diamond mining process, here’s a little tutorial.
First of all, diamond mines are found at the surface of what are called diamond stability zones. These are the primary sources when it comes to diamond mining. Stability zones are areas within a continent that are stable enough to maintain the structure of kimberlite pipes – we’ll get to those later. These diamond stability zones are found about 90 miles deep within the Earth’s crust where the temperature reaches about two-thousand degrees Fahrenheit. This is the ideal environment for diamonds to grow, which explains why diamonds have mystified humans for as long as we’ve been aware of their existence.
Well, it would be nice if there were a way to detect these diamond stability zones in the Earth, but unfortunately, things are a little bit more labor intensive than that. The first thing we have to do is follow the secondary sources back to the primary sources. These are often places such as rivers, ravines and streams. That’s because once the loose diamonds make their way to the surface of the Earth’s crust, they naturally migrate like any other sediment through the process of erosion. Once a trail of diamonds is discovered, that trail is followed to its source, and then it’s time to break ground.
Without kimberlite pipes, we would have no idea that those miraculous little stones were deep down in the Earth, spinning around the sun with us for millennia. Kimberlite pipes are the vessels that carry the loose diamonds from their stability zones to the surface. These pipes are lined with Kimberlite ore, this kimberlite ore carries the loose diamonds, and together they erupt to the surface and erode together slowly toward the ocean. Once the kimberlite pipes are found, shanks are placed in the ground and enormous amounts of soil are extracted. In some cases, hundreds of tons of dirt are extracted, transported to processing plants and then sieved, only to yield a single carat of stones that are gem quality diamonds.
There’s another type of mining that involves processing the kimberlite ore from secondary sources, such as rivers. In order to make this happen, entire portions of a river will be diverted so that the kimberlite ore can be extracted, transported and processed. This technique can be extremely damaging to the ecosystems it affects and often yields much less diamonds.