While sorting through the gems freshly unearthed in Yakutia, Russia, specialists working with the mining company ALROSA stumbled across something they’d never seen before: a tiny diamond entombed in the belly of a larger diamond. The so-called matryoshka diamond, named after Russian nesting dolls, weighs a mere 0.124 grams, and the outer gem is about as wide as a grain of rice is long, according to ALROSA’s announcement about the find last week.

Diamonds frequently act like tiny time capsules, capturing exotic minerals or traces of the soupy liquid that birthed them. But the discovery of an itty-bitty diamond rattling around inside a natural case of more diamond has stunned researchers.

“I thought, Holy cow, I never saw anything like