Botswana expected to receive the approvals within the next two months.
It started drilling in mid-February and has already completed the first phase of 18 drill holes to define the bulk sampling plan, with kimberlite found in 12 of them. It also identified a bulk sampling target of 1.5km of kimberlite fissure intersection.
The company had planned to do a total of 40 reverse circulation boreholes to a depth of 30m, with completion expected within four weeks from February 18.
Botswana has started the second phase of drilling on the farm Frischgewaagt, with all three holes drilled so far having intersected kimberlite.
One hole hit a 4.5m kimberlite intersection, the thickest to date, as well as discovered a mantle xenolith, which the company said was indicative of high diamond content.
Botswana said the third phase of drilling will start on two adjacent sites after a detailed gravity survey has been finished over two potential kimberlite blows on the same property, while a gravity survey is also underway.
The company is refurbishing the nearby diamond processing plant, which will process the bulk sample kimberlite and, later, material from Thorny River.
It has also started work on potential secondary diamond deposits in the project area, as the nearby and worked-out Marsfontein mine was host to eluvial diamond deposits with grades of 1,433 carats per hundred tonnes.
In June, Botswana completed Thorny River's technical and economic study, which indicated potentially positive economics using the top end of the 46-74cpht grade and US$120-220 per carat value ranges.
Botswana Diamonds' shares rose 9.6% Thursday after the news to 82p (US$1.08), with shares up 20.6% since the start of the year.