A small-scale miner in Tanzania has earned 7.74 billion Tanzanian shillings ($3.35m) after selling to the state the two largest tanzanite stones ever found.

The dark violet-blue gemstones, each about the size of a forearm, were discovered by Saniniu Laizer in one of the tanzanite mines in the north of the country which are surrounded by a wall to control cross-border smuggling of the gemstones.

“Today’s event … is to recognise the two largest tanzanite gemstones in history since the beginning of mining activities in Mirerani,” Simon Msanjila, mines ministry permanent secretary, said at a ceremony on Wednesday in Simanjiro district in Tanzania’s northern Manyara region.

Tanzanite is a gemstone found only in a small northern region of Tanzania.

The first gemstone weighed in at 9.27kg (20.4 pounds) while the second weighed 5.103kg (11.25 pounds), a mines ministry spokesperson said.

Laizer was pictured on Tanzanian television being presented with a large cheque after the country’s central bank bought the gemstones. President John Magufuli phoned to congratulate Laizer live on television.

Tanzania last year set up trading centres around the country to allow artisanal miners to sell their gems and gold to the government.

Artisanal miners are not officially employed by any mining companies and usually mine by hand.-Al Jazeera