'Trillions of carats' lie below a 35-million-year-old, 62-mile-diameter asteroid crater in eastern Siberia known as Popigai Astroblem. The Russians have known about the site since the 1970s.
Russia has just declassified news that will shake world gem markets to their core: the discovery of a vast new diamond field containing "trillions of carats," enough to supply global markets for another 3,000 years.
They decided to keep it secret, and not to exploit it, apparently because the USSR's huge diamond operations at Mirny, in Yakutia, were already producing immense profits in what was then a tightly controlled world market.
The Soviets were also producing a range of artificial diamonds for industry, into which they had invested heavily.
The veil of secrecy was finally lifted over the weekend, and Moscow permitted scientists from the nearby Novosibirsk Institute of Geology and Mineralogy to talk about it with Russian journalists.
According to the official news agency, ITAR-Tass, the diamonds at Popigai are "twice as hard" as the usual gemstones, making them ideal for industrial and scientific uses.