Gem weights in at 27.85 carats, and may become the most expensive polished diamond in the company's history.
Like a Russian nesting doll, one diamond is inside another.
Giant gem goes on show as Siberian diamond company Alrosa issues a 16% stock float.
A 44 per cent decline in diamond production was announced by Russian gem producer Alrosa.
Proceeds of a sale of a stake in Alrosa diamond giant will benefit local people, vows governor.
The Popigai reserves are enough to keep the planet in diamonds for 3,000 years.
The Siberian producer - owned mainly by the Russian state and the Sakha government - hopes to shine on the international market.
The world's top diamond producer is on course for a $10 billion valuation, say analysts.
A deal worth at least $60 million a year is close between Russia's largest diamond mining company and the US giant Tiffany & Co.