Understanding the Diamond commodity

Diamonds have long been symbols of luxury, durability, and unmatched beauty — but behind the sparkle lies a highly complex and technically demanding commodity. In July 2025, Multotec hosted a detailed Diamond commodity training session, presented by Richard Haydon, to equip staff with a well-rounded understanding of how diamonds are formed, recovered, and valued — and how Multotec’s range of products supports operations throughout this unique value chain.

Whether you’re in sales, manufacturing, or engineering, understanding how our solutions fit into the diamond recovery process helps us all drive better results, smarter decisions, and long-term value for clients.

The science beneath the sparkle: origins of diamonds

Diamonds are formed from carbon under extreme pressure and temperature, deep within the Earth’s mantle — around 200 km beneath the surface. These conditions occur in a zone called the diamond stability field, and diamonds are brought to the surface through volcanic eruptions in host rocks like kimberlite and lamproite.

Globally, about 5 000 kimberlite pipes have been discovered, yet fewer than 2 % of these are viable for commercial mining due to insufficient diamond content. The rarity of such economically mineable pipes directly influences the commodity’s value. The Argyle mine in Australia is a well-known example of a lamproite diamond deposit.

Interestingly, not all diamonds come from deep-Earth activity.

Some are formed from meteor impacts (impact diamonds), and others are lab-grown — a growing category competing with natural stones in both the jewellery and industrial sectors.

Diamonds can be found in both primary deposits (the original kimberlite or lamproite source) and secondary deposits (such as rivers and beaches, where diamonds have been naturally transported). These secondary sources are often exploited by artisanal miners, using basic tools like sieves and pans in labour-intensive processes

What makes a diamond valuable?

A diamond’s value is most commonly determined by the 4 C’s: Cut, Colour, Clarity, and Carat weight. Gem-quality diamonds, large, clear stones with minimal impurities, are rare, and this scarcity drives their high market value. Although we often associate diamonds with jewellery, 90 % of mined diamonds are used in industrial applications due to their exceptional hardness, thermal conductivity, and resistance to chemical corrosion.

Market trends indicate that while diamond prices have softened recently due to global economic pressures, including inflation and high interest rates, moderate growth is forecasted from 2027 to 2029.

This recovery is expected to be supported by:

• Improving consumer confidence and jewellery demand.
• Demand for ethical and sustainable diamonds
• Supply controls by leading producers

However, competition from lab-grown diamonds and alternative luxury goods will continue to challenge traditional markets. Younger consumers, particularly Gen Z and Millennials, are placing more value on sustainability and ethical sourcing — reshaping the narrative around what makes a diamond desirable.

How are diamonds recovered?

The recovery of diamonds from ore is highly technical and requires a variety of process steps to separate the valuable material from waste. These include:

1. Dense Medium Separation (DMS):
   A primary method for separating diamond-bearing ore based on density differences, DMS uses a heavy media such as ferrosilicon (FeSi) in cyclones to isolate heavier particles like diamonds.
2. Grease Plants & Flotation:
   Diamonds are hydrophobic, meaning they repel water. Grease plants take advantage of this by using greasy surfaces to collect diamonds. Flotation techniques condition the ore with oils and fatty acids to make fine diamonds float to the surface.
3. Automated X-ray Sorting (XRL/XRT):
   Using X-ray luminescence (XRL) or transmission (XRT), these systems detect diamonds based on their ability to reflect or transmit X-rays. XRT is especially useful for larger or Type II diamonds and doesn’t require the particles to be fully liberated.
4. Colour and RAMAN Sorters:
   Advanced technologies that identify diamonds based on surface properties or crystal structures, often used in downstream or final recovery stages.
5. Jigs and Rotary pans:
   Older methods still used in some operations, primarily for bulk material processing, although less efficient than newer automated systems.

Multotec’s role in diamond recovery

Multotec supplies an extensive range of products specifically engineered to meet the demands of diamond processing plants:

DMS cyclones: Used in media separation, made from durable cast iron or wear-resistant linings.

Screening Media: Heavy-duty rubber panels and wedge wire panels suited for primary and dewatering screens.

Wear linings: Industrial ceramics, cast basalt, and composite linings for chutes, pipes, and scrubbing units — including Multoslip coatings for sticky ore.

Sampling solutions: In-plant samplers ensure secure, representative samples, critical for plant audits and recovery monitoring.

Slurry pumps & VSP sumps: Designed for reliable operation in abrasive and high-volume slurry systems.

Tailings decanters: Offer an effective alternative to filter presses in clay-rich diamond tailings, delivering stackable cake material.

Our presence in diamond operations includes Letseng, Venetia, Williamson, and Liqhobong, among others further demonstrating Multotec’s proven reliability in high - value, high-precision mining environments.

Diamond mining and recovery takes place in various forms, from alluvial sources to underground mining. A range of mineral processing flow sheets, from simple to highly automated, can be applied. Thanks to our broad product offering and extensive experience, we are able to supply solutions that help improve diamond recoveries.

RICHARD HAYDON, Product Specialist – Cyclones, Multotec