Diamond rough crystal

Rough diamond crystal, the natural uncut form of the hardest known mineral, mined from kimberlite pipes in regions like Africa, Russia, and Brazil.

About this subject

A rough diamond crystal is the natural form of carbon crystallized under extreme pressure and temperature deep within Earth's mantle, over billions of years. These octahedral or dodecahedral crystals feature rough surfaces and natural inclusions, contrasting with the faceted brilliance of cut diamonds. Primary deposits occur in kimberlite pipes, ancient volcanic rocks, with major producers including Botswana, Russia, Canada, and Angola. In Brazil, diamond mining started in the 18th century in Minas Gerais, especially in Diamantina, and today takes place mainly in Rondônia and Mato Grosso, yielding crystals up to 10 carats. The Mohs hardness of 10 makes diamond ideal for drill bits, cutting blades, and industrial abrasives. About 80% of global production is used industrially, while 20% goes to jewelry. Natural colors arise from impurities: nitrogen causes yellow, boron gives blue, and structural defects produce pink or green hues. The crystal's shape directly affects cutting yield, with octahedral being most common and efficient. The largest rough diamond ever discovered is the Cullinan, found in South Africa in 1905, weighing 3,106 carats.

Frequently Asked Questions

What is the difference between rough and cut diamonds?

Rough diamonds are natural stones as mined, with uneven surfaces and inclusions. Cut diamonds have been shaped and polished to enhance brilliance and symmetry, used in jewelry.

Where are rough diamonds found in Brazil?

The main producing states are Minas Gerais (Diamantina region), Rondônia, Mato Grosso, and Bahia. Mining occurs in alluvial deposits and kimberlite pipes.

How are rough diamonds evaluated?

Evaluation considers carat weight, color, clarity (inclusions), and crystal shape. Quality determines whether they are used for gemstones or industrial purposes.