GIA Examines Alrosa's Matryoshka Diamond

RAPAPORT... Alrosa's unusual diamond-within-a-diamond formed when material partially dissolved over millions or billions of years, according to a report by the Gemological Institute of America (GIA).The GIA's team, which examined the stone at its New York lab, found that over time, approximately 0.11 carats of diamond disappeared through two small channels that extended from the surface of the diamond to its inner cavity. The remaining diamond material created a 0.03-carat crystal that is entirely detached and moves freely within its outer diamond shell, the institute said last week."We have never seen anything like this," said Tom Moses, GIA's executive vice president and chief laboratory and research officer. "This is a truly unusual diamond, not only for the fact that there is a small diamond crystal inside, and entirely detached from the host crystal, but also for the mystery of how this diamond-in-a-diamond formed."Alrosa discovered the diamond last year during sorting at its Nyurba division in Yakutia. The miner, which said the diamond was the first of its kind in history, named the stone Matryushka, after the Russian term for nesting dolls.The inner and outer diamonds had nearly identical "trace elements" -substances found in small quantities within the stone. That confirmed they were initially one solid diamond without the cavity, the GIA explained. The original diamond had been naturally irradiated, based on the clear-green color of the inner stone and etchings on its surface that resembled Christmas trees. Those patterns were caused by fluid containing radioactive elements that seeped through shallow fractures along the diamond's edges, the GIA noted."Examining this nesting-doll diamond was a remarkable opportunity," Moses said. "The opportunity to examine this special diamond-within-a-diamond added to our understanding of how diamonds form."Image: The Matryoshka diamond. (Jianxin (Jae) Liao/GIA)