A diamond containing another, free-moving gem inside unearthed from a mine in Siberia is the first stone of its kind in recorded history, Russian state mining company Alrosa PJSC said Friday.

The diamond may be more than 800 million years old, Alrosa said in a statement.

Dubbed the Matryoshka diamond in reference to the Russian nesting dolls of that name, the stone weighs 0.62 carats, while the internal gem weighs 0.02 carats, the company said.