(IDEX Online) - De Beers has announced the discovery of an astonishingly rare diamond-within-a-diamond.The 0.329 carat D-color Type IaAB diamond, named the Beating Heart has an internal cavity enclosing a smaller diamond that is trapped yet able to move freely.There are only two other known examples of such a Matryoshka or Russian Doll diamond.In 2019, Alrosa recovered a 0.62 carat diamond at its Nyurba mining and processing division in Yakutia. It had an internal cavity containing a tiny diamond with an estimated weight of 0.02 carats.In 2021, India Bore Diamond Holdings (IBDH) found an 0.844-carat flat, triangular gem at the Ellendale alluvial deposit, in Western Australia. It had a cavity containing another tiny diamond, reckoned to be just 0.001-ct.The origins of the newly-discovered Beating Heart are unclear. It was unearthed at a De Beers mine in Botswana, Canada, Namibia or South Africa, and spotted after it reached VD Global (VDG), in India last October.It was then sent to the De Beers Institute of Diamonds (IoD) facility in Maidenhead, England, for examination."Initial conclusions suggest the cavity was formed due to preferential etching of an intermediate layer of poor-quality fibrous diamond," said the IoD."The original 'core' would have consisted of good-quality diamond growth. However, a subsequent layer of growth was likely poor and fibrous, followed by a further 'outer coating' of gem-quality crystal. At some point between its formation and travel to the surface of the Earth, the poor-quality layer etched away. "Only the better quality material 'survived' this process - the outer diamond and the core - which, in this case, led to a diamond that can freely move around within an inner space."The diamond will not be cut and polished. It will be kept for research and educational purposes.Photo: Danny Bowler/Institute of Diamonds