Russian central and regional government officials are moving ahead with a drive to raise cash from state-owned assets, agreeing to slash interests in diamond miner OAO Alrosa within the gem industry’s largest share sale — at $1.6 billion — in more than a century. Alrosa produces 25% of the world’s diamonds by value.

Alrosa, with origins dating back to the first Russian diamond mine discovery in the 1950s, has been growing production in recent decades, overtaking Anglo American-owned De Beers in 2009 as the world’s top diamond producer by volume; it still lags in value terms, however.

Under the offering, planned since the early 2000s, Russian federal and regional government officials will sell 14% of Alrosa shares, using cash to bolster finances. A further 2% will be sold by an Alrosa unit; proceeds will be used to pay down debt. The company has a free float of 9% on the Moscow market.

Alrosa declined to comment, according to Reuters, though in Q2 CEO Fyodor Andreev put the company’s value at between $9 billion and $15 billion. Following the sale, Russia’s federal and regional governments will own 43.9% and 25%, respectively. Currently, Alrosa is 50.9% Russian-owned and 32% owned by the Republic of Yakutia.

Alrosa’s main assets lie in Yakutia in Russia’s Far East, a remote region of tundra and forest, and the country’s largest province, also a repository of large deposits of natural resources from oil and gas to gold and coal.

Alrosa will be one of very few pure listed diamond miners — its nearest rival is London-listed Petra Diamonds, with a market capitalization of less than $1 billion. But it could remain out of reach for many, as listed in Moscow. Apart from mines in Russia, Alrosa is also a shareholder in the Catoca mine in Angola, the sub-Saharan country’s largest.