Unique diamond inside a diamond found in Russia

Miners in Russia have made a rare discovery, unearthing a hollow diamond with another diamond inside.

The group from the ALROSA mining company in Yakutia were digging last week when they discovered the matryoshka diamond, named after Russian nesting dolls.

The gem, believed to be the first of its kind found, weighs just 0.124 grams and is about the length of grain of rice.

"This is really a unique creation of nature," Oleg Kovalchuk, deputy director for innovations at ALROSA's Research and Development Geological Enterprise said in a statement.

Scientists are perplexed over how the diamond came to be hollow, since the amount of pressure the Earth's mantle uses to form diamonds should have completely solidified it.

ALROSA plans to send the unique stone to the Gemological Institute of America to try and figure out how it came to form that way.

According to National Geographic, water may have worked its way into the forming rock and dissolved some of the inside material before it solidified. Another suggestion is that a pre-existing salty fluid may have leaked out leaving the smaller diamond in the cavity.