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Diamond-in-diamond, first of its kind, unearthed

Alrosa’s matryoshka diamond discovery weighs just 0.62 carats. On the right is an X-ray image of the stone.
Alrosa’s matryoshka diamond discovery weighs just 0.62 carats. On the right is an X-ray image of the stone.

A diamond akin to a traditional Russian nesting doll has been recovered by Alrosa.  

The stone, which weighs just 0.62 carats, has an internal cavity of 6 mm3. Within this space, Alrosa reports, is a second diamond with an estimated weight of 0.02 carats.

Due to its peculiarity, the diamond resembles a traditional Russian matryoshka doll (or nesting doll)—and it may be the first of its kind.

“As far as we know, there were no such diamonds in the history of global diamond mining yet,” says Oleg Kovalchuk, deputy director for innovations at Alrosa’s research and development geological enterprise. “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.”

The diamond was found at the mining company’s Nyurba site in Siberia and its formation may date back more than 800 million years, Alrosa says.

The external stone carries maximum dimensions of 4.8 by 4.9 by 2.8 mm, while the inner diamond has a tabular shape and dimensions of 1.9 by 2.1 by 0.6 mm.

The discovery was analyzed at Alrosa’s research and development geological enterprise using several methods, including Raman and infrared spectroscopies, as well as X-ray microtomography.

Scientists determined the internal diamond likely formed first and the external developed during subsequent stages of growth.

“The most interesting thing for us was to find out how the air space between the inner and outer diamonds was formed,” Kovalchuk says.

“We have two main hypotheses: according to the first version, a mantle mineral captured a diamond during its growth, and later it was dissolved in the Earth’s surface.

“According to the second version, a layer of porous polycrystalline diamond substance was formed inside the diamond because of ultra-fast growth, and more aggressive mantle processes subsequently dissolved it. Due to the presence of the dissolved zone, one diamond began to move freely inside another on the principle of matryoshka nesting doll.”

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To see the stone in action, check out the video below, courtesy Alrosa.

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