All diamonds are produced in the same way. I mean they are all produced by volcanic action - the right combination of heat and pressure and rock - and you get those pipes as we saw in the clip. It is a small volcano that pushes rock and gravel and what is known as kimberlite to the surface. These are small almost carrot-like volcanoes. They are not mountains. They can be very small. The surface could be - the surface of a kimberlite with diamonds could be half the size of this room. The biggest ones that have diamonds are probably no more than half a kilometre across. So, all diamonds are formed in that way.
When you are prospecting for diamonds, you may find a kimberlite pipe intact - this is what happened in Canada, it is what you find in Botswana and some of the Russian mines - and in that case you simply put a fence around the mine and you dig down into the pipe, you bring up the rock, the gravel, you sort out the diamonds and basically that is how the mining is done.
But diamonds were all formed more than 50 million years, ago, in some cases much, much farther back than that, and in some places the tops of these kimberlite pipes have been worn away. 50 million rainy seasons wearing away the top of a diamond pipe will scatter the diamonds that were included in it far and wide. The pipe itself may still be there, but the top ten, or 15, or 20 feet may be gone.
Those diamonds are called alluvial diamonds; meaning river. They come - they are washed away by rivers in some cases down towards the sea. In many cases, the rivers no longer exist. They are not easy to trace in some cases. In other cases, as in Namibia, almost all of the alluvial diamonds have actually worn right out into the ocean and so all of the might is done offshore. They have ships that basically hoover up the diamonds from the ocean floor.
The issue with many alluvial diamonds - and this is what you have in Sierra Leone, in many places in the Congo and parts of Angola, in Liberia and Guinea - the kimberlite pipes remain in some cases, but there are diamonds scattered over hundreds of square miles. These are alluvial diamonds and they may be anywhere from within an inch below the surface. They sometimes are even spotted on the surface. They could be as much as ten or 15 feet below and you may need to dig down quite far to get them, but you don't need a lot of heavy equipment as in the case of a kimberlite mine.