It is not unusual for De Beers to find a diamond. But it’s certainly rare for the diamond giant to find a piece of rough that contains a second gem.

Recently, the De Beers Institute of Diamonds, the company’s lab and educational arm, announced the discovery of a 0.3 ct., D-color, type IaAB diamond with an internal cavity that housed another rough diamond. The second, smaller rough was trapped inside the larger diamond, but could move around freely inside it.

The unique De Beers-mined specimen was flagged in October 2022 by VD Global, an India-based De Beers sightholder, which dubbed it “The Beating Heart.”

The diamond will be left in rough form, so it can be studied.

The De Beers Institute believes the original internal diamond had a core of good-quality diamond growth. However, its subsequent growth layer was likely poor and fibrous, and was covered by an outer coating of gem-quality crystal.

At some point—after the diamond was formed in the center of the Earth but before it took the great “conveyor belt” ride to the surface—the poor-quality layer fell away. Only the better-quality material—the outer diamond and the core—survived the process.

“The Beating Heart is a remarkable example of what can happen on the natural diamond journey from formation to discovery,” said Jamie Clark, head of global operations at the De Beers Institute of Diamonds, in a statement. “A find like this demonstrates why natural diamond formation and origin is such a fascinating area of study.”

This is not the first discovery of this type: In 2019, Russian diamond miner Alrosa also unearthed a diamond within a diamond, which it named the “Matryoshka” diamond, after the famed Russian nesting dolls.