The Diamond Pipeline

The “diamond pipeline” is generally referred to as the process of unearthing rough gemstones, classifying them, polishing them and marketing them. But in truth, the diamond industry’s supply chain does not begin at the mine. Diamond exploration, a vital undertaking for sustaining the diamond trade, must also be taken into account. The discovery of potential mining locations entails satellite imagery processing, geological mapping, chemical analyses of soil samples and networks of exploration laboratories and drilling sites. The world’s leading diamond companies are currently engaged in intensive exploration activities in such far and wide locales as Russia, Australia, India, Brazil, Canada and South Africa.

There are two established diamond mining methods: “Pipe mining” is the extraction of diamonds from volcanic pipes composed of kimberlite, a type of  igneous rock. Using shafts and tunnels, the diamond bearing rock is extracted and brought to the surface. Typically, some 250 tons of ore must be mined in order to produce a one-carat diamond. “Alluvial mining” is the removal of diamond bearing rock from riverbeds and beaches. The shoreline operation entails the construction of walls to hold back the ocean surf and bulldozing up to 25 meters of sand to reach the diamond yielding level.

Once the rough diamonds are extracted, they are brought to sorting stations for classification. This process employs both diamond sorting experts and government diamond assessors to establish a fixed value before passing the diamonds on to the next stage of the pipeline. Since the stones are still in their uncut state, the sorting operation emphasizes Color and Clarity. At the sorting level, only 20% of the world’s mined diamonds are classified as gem quality. The remaining 80% is classified as industrial quality or “boart,” some of which is crushed and used in the subsequent diamond polishing process. Diamonds designated for industry are used primarily for cutting, sawing and drilling. The term “diamond drilling” refers to the diamond-tipped drills used in drilling operations for oil, natural gas and minerals, including diamonds.

Upon completion of the sorting phase, gem quality diamonds are passed on to a diamond manufacturer for the crucial diamond polishing process, which essentially determines the stone’s Cut and turns it into a ready-for-market diamond gem. The Cut of the diamond, considered by diamontaires to be the most important of the 4 Cs, entails manual cleaving or sawing the rough diamond with laser or a diamond tipped rotary saw; shaping the diamond by “bruting” it, i.e. forcing another diamond against it on a rotating lathe; and the conclusive polish which forms the diamond’s facets, smoothens its final proportions and empowers the diamond to “catch fire” and display its brilliance.
Once polishing is completed, diamond traders can assess the value of the precious stone on the basis of a grading process which classifies the diamond’s 4 Cs, symmetry, proportions and other vital characteristics. In many instances, a diamond’s valuation is authenticated by means of grading certification at the hands of independent gemologists and diamond appraisers. With its grading in place and retail value set, the diamond is primed for the market.