Paragon Diamonds (LON:PRG) has applied for a licence that will allow the group to begin trial mining at its flagship Lemphane kimberlite in Lesotho.
The news was part of a wider update, which included results of a high level scoping study of the project.
This assessed the potential of a 27 million-tonne open pit down to 280 metres based on six hectares of kimberlite.
It was concluded the mine life would be 10 years at 1.5 million tonnes a year initially, rising to 3 million after two years.
The waste to ore ratio would be 1.3-to-1, and the costs are put at somewhere in the order of US$15 a tonne, Paragon said. The pit is projected to take 12-18 months to construct.
Separately, drilling of the Lemphane kimberlite continues, with 775 metres completed to date of a total in excess of 2,000 metres.
At the same time, bulk sampling of the remaining 15,000 tonnes of material has restarted and should be completed by June.
Trial mining is slated to begin in the second half and will process around 100,000 tonnes of kimberlite.
Paragon chairman Martin Doyle said: "I am pleased to report the successful completion of another key milestone for the project, being the submission of the mining licence application which will enable us to progress towards trial miming.
“The drilling is progressing as planned and with the effective solution to the water supply issues I look forward to bringing the plant up to full capacity and to updating the market on the bulk sampling and eventual trial mining programme over the coming months."