Sorting and Valuing

A shipment of rough diamonds is received at the DTC

Even though every rough diamond is unique, buying and selling them depends upon assigning value to agreed standards of size, shape, colour and clarity. De Beers combines these factors into 12,000 different, identifiable categories of diamonds.

Deciding how to classify any given diamond is a task that requires skill and experience. It is at the heart of what we do.

Sorting diamonds

Diamond sorting is carried out sorting offices in Gaborone, Kimberley and Windhoek.

Each of these offices has its own dedicated training academy to prepare diamond sorters to an expert level that is respected throughout the industry.

Much of the sorting operation is still carried out by experts using traditional loupes. However, in recent years, our use of proprietary advanced technology to accurately and rapidly sort larger volumes of smaller stones has given us and our producing partners competitive advantage. Technology research at our R&D facility in Maidenhead, UK emphasises simplified processes and improved value-added assortments.

Buying diamonds

We receive diamonds from our mines in South Africa and Canada and purchase diamonds from our joint venture producer partners in Botswana and Namibia. The process of agreeing value is carefully considered:

  • In the interest of fairness, separate diamond sorting experts represent both De Beers and the government diamond valuers (GDVs) of our joint venture partners
  • Sorters classify the diamonds by comparison with master reference samples. Any disagreements are settled by reference to these samples
  • Each diamond category corresponds to a price in the Global Sightholder Sales proprietary price book. Once categorisation is agreed, the purchase can proceed on an agreed price

Aggregating diamonds

As a last stage, before offering diamonds to our clients, known as Sightholders, diamonds of the same category, regardless of origin, are blended. This improves the consistency of diamonds in a given category that are supplied to the Sightholders.

Senior Sorter Leititia Makapela inspects a diamond on the sorting floor at Harry Oppenheimer House in Kimberley