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Rough Diamonds

The octohedran 232-carat rough diamond, discovered by Alrosa on October 19, 2019.





Alrosa, the state-controlled Russian diamond mining company that currently is the world’s leading diamond producer by output, has reported the discovery of a very large rough diamond, weighing more than 232 carats. The company says that it is largest gem-quality rough diamond found in more than three years.

“Such large gem-quality crystals are extremely rare,” stated Alrosa’s deputy chief executive, Evgeny Agureev. “We have not seen them since 2016, when two diamonds weighing over 200 carats were mined.” 

The diamond was discovered on October 19, 2019, at the Udacnhaya mine in Yakutia, the autonomous areas on northeastern Siberia where most of Russia’s diamond deposits are located. 

The rough stone is octahedron in shape with a yellowish hue with several chips. Its dimensions are 4.0 centimeters by 3.90 centimeters by 2.3 centimeters.


Udachnaya was discovered on June 15, 1955, just two days after the discovery of the better-known Mir kimberlite, upon which the Russian diamond industry was originally created.

Today Udachnaya the kimberlite pipe is one of the largest primary diamond deposits in the Yakutia region of Siberia and globally. Its diamond output reached 2.39 million carats in the first nine months of 2019.

The Udachny open-pit mine came on stream in 1971, and reached its maximum depth of 640 meters by 2015. The adjacent Zarnitsa open-pit mine has been operating since 1999. Currently about 100 meters deep, it eventually will reach a design depth of 200 meters.

The Udachny underground mine was launched in 2014.  It will become one of the largest underground mines in the world, after reaching a per annum output of about 4 million tons of ore.

Alrosa produced more than 43 million carats of diamonds in 2018 from its Russian mines, or about 27 percent of the world’s total. That is 18 percent more than its closest competitor, Anglo American’s De Beers.

Mining operations at Alrosa’s Udachny mine in the northeastern Siberia autonomous region of Yakutia.

The “Matryoshka” diamond,  with a 0.6-carat outer stone encapsulating a  0.02 carat inner diamond.


The 232-carat stone was not the only stone mined by Alrosa to make news this months. It earlier was a reported that the company had discovered the first-ever diamond within a diamond.

Calling it the “Matryoshka” diamond for Russia’s popular nesting or stacking dolls, also known as Babushka dolls, the outer stone small is just 0.62 carats and 4.8 millimeters by 4.9 millimeters x 2.8 millimeters. The internal or nesting diamond, which is inside a closed cavity where it can move freely, is even smaller.  It has an estimated weight of just 0.02 carats and dimensions of 1.9 millimeters × 2.1 millimeters × 0.6 millimeters.

Scientists working for Alrosa believe that the internal diamond formed first and was then enclosed by the larger crystal. “This is really a unique creation of nature, especially since nature does not like emptiness. Usually, some minerals are replaced by others without cavity formation,” said Oleg Kovalchuk, Deputy Director for innovations at the company’s Research and Development Geological Enterprise.