Diamonds that come straight from the mines where they are unearthed are called "Run of Mine" diamonds. This term refers to a mixed collection of diamonds of various sizes, shapes, and qualities. These diamonds require careful sorting and grading to prepare them for the market, where they can be sold to meet the specific demands of buyers and industries.

So, sorting is the first critical step in the diamond supply chain. Once rough diamonds are extracted from mines, they are sent to sorting facilities, where specialists examine them to determine their characteristics. The goal is to classify diamonds into categories based on size, shape, quality, and potential market use. Sorting ensures that diamonds are effectively matched with their most appropriate applications, whether destined for fine jewelry or industrial tools.

The process begins with a preliminary sorting, focusing on basic attributes like size and shape. At this stage, diamonds are separated into broad categories, allowing specialists to identify stones that require more detailed evaluation. Further sorting examines clarity (internal and external imperfections), color, and the stone’s potential yield after cutting.

One of the primary objectives of sorting is to maximize the value of each diamond. This involves estimating the potential weight and shape of the polished diamond that could be produced from the rough stone. Advanced technologies, such as 3D mapping and scanning, aid in identifying the best cutting and polishing strategies, ensuring that the maximum value is extracted from each diamond.

Diamonds are ultimately sorted into three main categories:

• Gem-Quality:

 These are the most valuable diamonds, used in fine jewelry.

• Industrial-Quality:

 These are less suitable for jewelry due to significant flaws or irregular shapes but are highly prized in industrial applications like cutting, grinding, and drilling tools.

• Near-Gem:

 Falling between gem-quality and industrial-quality, these stones are often used in lower-grade jewelry or specialized industrial applications.

Sorting ensures the smooth transition of diamonds to the next stages in the supply chain, with clarity, precision, and efficiency driving the process.

Once sorted, rough diamonds enter the trading phase. 

Rough diamonds are primarily traded among industry professionals, including mining companies, manufacturers, and diamond dealers.

The global rough diamond trade operates through several channels:

• Tender Systems and Auctions:

In tender systems and auctions, rough diamonds are offered to the highest bidder in a transparent and competitive environment. Buyers, often manufacturers or traders, have the opportunity to inspect and assess the stones before placing sealed bids. Auctions are widely regarded as one of the fairest ways to sell diamonds, as the final price reflects true market demand. Tender systems also allow smaller mining companies to bring their production to market efficiently. For instance, companies operating in Africa often use Antwerp as a venue to showcase and sell their rough diamonds in tenders.

• Long-Term Supply Contracts:

Many major mining companies prefer long-term contracts with select clients, known as sightholders or contract clients. These agreements provide stability for both parties: the supplier is guaranteed regular sales, while the buyer secures a consistent supply of rough diamonds. This model is often used by larger players in the industry.

• Open Market Transactions:

In the open market, diamonds are traded more freely, with brokers, traders, and smaller companies buying and selling parcels in secondary markets. These transactions often occur in trading hubs or at diamond bourses, which are highly secure exchanges specifically designed for the trade of diamonds.

Key trading centers around the world facilitate these transactions, with Antwerp standing out as a global leader. The city’s diamond district is home to numerous diamond companies, grading laboratories, and specialized trading offices.