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Rough Diamonds

Diamonds in their original state are called rough diamonds: Before they are cut and polished, the way they look after finding their way up to the surface from more than 150 km deep inside the earth´s crust. They might appear quite dull and hazy and the untrained eye might mistake them for a chunk of glass that has been washed up on the shore. The most common colors range from colorless, over yellow to brown. The skill and expertise of a diamond cutter is needed to light a diamond´s fire and brilliance. Only a rather small percentage of all mined diamonds are actually suitable for jewelry. The majority ends up being sold for industrial usage.

The images above show from left to right the rough diamond, the planning stage and the polished product.

In comparison to polished diamonds that are easy to compare using the 4 C it is rather difficult to evaluate rough diamonds. This is true especially because nobody can say before cutting and polishing the stone to what extend the material can be exploited and what price the final product will be able to yield. Here one needs to rely on the rich experience of skilled traders of rough diamonds. At the same time technological advancements also change the old fashioned diamond trade: Nowadays there are 3D laser scanners and software that can calculate the highest possible yield of any rough stone before being cut. These developments have a great impact on the amount of diamonds suitable for jewelry and ensures better planning reliability.


A unique role in the world of diamonds plays the city of Antwerp in Belgium. With more than 500 years of being the center for diamonds and the diamond trade, Antwerp is up until today a major hub of the industry: 80% of all rough diamonds (per volume) and more than 50% of polished diamonds are traded in Antwerp. The first diamond exchange that specialized in rough stones, the "Antwpersche Diamantkring", was founded in 1928 and is an important member in the delivery chain of diamonds. From there the precious stones find their way to the cutting and polishing centers in India, Israel or New York where they get their brilliance and fire.

The 187.7 carat Diavik Foxfire is one of the largest diamonds ever discovered in Canada
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 The largest ever to be found rough diamond was the orginal stone of the Excelsior diamonds. It weighed an incredible 995.2 carats (194 g) and was found 1893 in the South African Jagersfontein Mine. However, since it was simply too big to be sold to one client only it was cut in 11 smaller pieces. No single person could have afforded a diamond of this size. The price for being able to sell the diamond was missing out on the opportunity to produce the largest polished diamond of all times.

Source: Wikipedia, Author: Edwin W. Streeter
More about the most famous diamonds

World production of diamonds in 2014

Volume (in carats)
% of world production
Value (in US Dollars)
% of world production
$ 8,445,556,346
$ 3,733,262,920
$ 2,003,267,161
$ 304,319,165

$ 14,495,806,402

The shape of rough diamonds shows distinctively: Diamonds crystallize cubically- and predominantly in form of a octahedron. Seeming rather unimpressive rough diamonds often resemble two pyramids on top of each other.


The Australian Argyle mine produces about 90% of the world´s pink diamonds and also exctracts large amounts of fancy colored diamonds of Champagne, Cognoc and somethimes even blue color. Yet, the ratio of volume to quality of all mined diamonds is rather low. Since most diamonds are not suitable for jewelry the Argyle mine has a rather low average diamond value compared to other mines.

Copyright © 2017 Rio Tinto