How Are Diamonds Mined?

We seldom think about how the diamonds we wear came to us. Natural diamonds, as opposed to synthetic diamonds or fake diamonds, are mined from the earth. There are currently two methods of mining diamonds: Pipe Mining and Alluvial Mining.

Pipe Mining
When pipe mining is used, the diamonds are extracted from the earth through volcanic pipes. These are not man-made pipes - they are natural pipes in the ground. Shanks are put into the ground next to the pipes, and tunnels are driven into the deepest parts of the pipe. The diamonds are not sorted out at the mine. Instead, huge rocks that are full of diamonds are brought out of the mine and moved to a screening plant for separation.

Alluvial Mining
The Alluvial mining method is done in riverbeds and on beaches. Walls are built to hold back the water and the sand on the bank or beach. The sand is moved with a bulldozer until the level of earth that diamonds can be found in is reached. Again, the diamonds are not sorted here. Instead, the sand that contains the diamonds is bulldozed into trucks, and taken to screening plants.

At the diamond screening plants, natural rough diamonds are extracted from the rocks and earth, and then undergo cutting and polishing, before finally becoming the diamonds we see on jewellery.

How Are Diamonds Cut?

In their most natural form, diamonds are, well, quite ugly. They have no luster or shine, and in fact, look like nothing more than broken glass. A diamond must be cut, and then polished before it actually becomes a thing of beauty.

Planning and Marking

A rough diamond is first examined by a planner to determined how it should be cut to yield the best value. The planner takes into consideration of the grain and crystal structure of the diamond to mark positions where it would be cleaved or sawed by the diamond cutters.

Cleaving

Large diamonds are separated into smaller pieces, by a process known as cleaving, that are suitable for further sawing. Cleaving is also done to quickly remove large unwanted pieces (usually areas with blemishes and other imperfections) from the rough diamond. This process is important as a wrong split will ruin the diamond and reduce the value of the diamond drastically.

The cleaver carefully cut grooves into the diamond at locations marked by the planner with another diamond. He then splits the diamond along the grooves with a mallet and a metal wedge. The diamond is now ready for sawing.

Sawing

Sawing shapes the diamond into various shapes such as heart, square, or the common round shapes. A circular disk saw is used to cut it down to shape. The cutting edge of the saw is initially coated with diamond dust in order to start the first few cuts. After the first few cuts, the cutting edge of the saw will coat itself with diamond dust from the diamond that is being cut. This maintains the hardness of the saw's cutting edge.

Girdling

The diamond is further shaped and its freshly cut edges are rounded by girdling. The diamond is mounted on a lathe and another diamond is used to grind it into shape.

Faceting

A diamond lapper or scaife that is coated with diamond dust is used to cut the facets. Faceting is the final and one of the most important steps in diamond cutting where the facets of a diamond is cut. The quality of the faceting that is being done will determine the brillance and fire of the diamond. Each facet of the diamond must be carefully cut into the geometrical shapes that allow maximum refraction and reflection of incident light.

Polishing

Polishing is the final step to transform a rough diamond into a diamond that is ready for sale. A diamond lapper is used, but with a different, finer lapping disk. The diamond is then finally ready for certification grading and sales or further setting into jewellery.