Sorting of Rough Diamonds


the destiny of a diamond

Diamonds, as we have seen, may come out the mine in a plethora of ways, but once freed they must all go through the same sorting process. Most commonly, the kimberlite which will eventually become an exquisite Backes & Strauss diamond watch for women and men will be taken to a processing plant. Here, it will be assessed, with the prime aim at this early stage to sort the diamonds based on their shape, size and crystallisation. It is an aim which will see only 20% of stones make it through to the next step, as the vast majority of diamonds, or bort, will never be worn and are destined to be used for industrial purposes only.

It is difficult to sort the rough diamonds at this early stage by eye, as they have a long way to go before they resemble the polished diamonds we see in Bond Street. Almost resembling broken glass in their jagged outlines and irregular colours, the eventual decisions on their clarity and cut must wait.

Various sorting methods

There are a few different ways of most efficiently separating these rough diamonds, with a series of rigorous tests ensuring the precious diamonds are carefully extracted. One method uses the high density of a diamond to tell them apart from the rest, using what is known as a washing pan which mixes crushed ore with muddy water, stirred briskly by rotating blades. The heavier diamonds slip safely to the bottom.

Another method, an X-ray machine, can also be helpful as it spots the diamonds that luminesce in its beam, which then activates a jet of air which separates them from the rest. While this has its benefits, it may not catch the valuable Type II stones. Grease tables are more useful here, as diamonds, which are naturally impervious to water, will stick to the grease while the wetter material slides off.

It is the stones, which are eventually classified as being more than one carat, and the beautiful gems in fancy diamond colours which will most pique the interest of the Backes & Strauss wearer. The rough diamonds which will go into creating a luxury, high-end diamond watch have been identified, but exactly what they will become remains, at this stage, a mystery.

Anna Vasiunyk