Diamond rough crystal

Rough diamond crystal in its natural octahedral form, unpolished, with matte surface and inclusions typical of diamonds extracted from kimberlite pipes.

About this subject

Rough diamond is the natural form of crystallized carbon found in the Earth's mantle, subjected to extreme pressures and high temperatures. Its crystal structure, typically octahedral or dodecahedral, features a rough, opaque surface far from the brilliance of polished gems. These crystals are brought to the surface by volcanic eruptions of kimberlite, a rock that forms diamond-bearing pipes.

Major diamond mines are located in Africa, especially Botswana, Russia, Canada, and Brazil. In Brazil, the Serra da Canastra region and Mato Grosso state are known for alluvial deposits where crystals are found in riverbeds. Most rough diamonds are destined for jewelry, but about 70% of global production is used industrially due to their unmatched hardness, the highest among all natural materials.

A fascinating curiosity is that the oldest known diamonds are over 3 billion years old, formed long before dinosaurs roamed the Earth. The largest rough diamond ever found was the Cullinan, at 3,106 carats, discovered in South Africa in 1905. Today, techniques such as X-ray diffraction and Raman spectroscopy allow identification of rough diamonds and distinguish them from imitations like moissanite.

Frequently Asked Questions

What is the difference between rough and cut diamond?

A rough diamond is the natural gemstone as mined, with a rough surface and no cuts. A cut diamond has been polished and faceted to enhance its brilliance, fire, and aesthetic value, typically used in jewelry.

How to identify a real rough diamond?

Rough diamonds are extremely hard, scratching other materials, and often exhibit octahedral or cubic crystal shapes. They conduct heat rapidly, detectable with specific devices, and have natural inclusions visible under magnification.

Where are rough diamonds found in Brazil?

In Brazil, rough diamonds are found in alluvial deposits in Minas Gerais (Serra da Canastra), Mato Grosso, Bahia, and Goiás, as well as the Amazon region. Mining is mostly done by garimpeiros in riverbeds.