Petra Diamonds (LON:PDL) said initial drilling and microdiamond analysis results indicate that kimberlite KX36, part of the Kukama East project in central Botswana, has significant potential.
The company will start a large diameter drilling programme next month to obtain a bulk sample.
Petra has now received results from work undertaken on KX36 last year, when a total of 1,373 metres was drilled in five holes and 250 diamonds, collectively weighing 0.756 carats, were recovered from 403.88 kilogrammes of kimberlite.
The largest diamond recovered was transparent white, weighing 0.393 carats.
An initial model puts the diamond grade for the kimberlite between 75 carats per hundred tonne (cpht) and 180 cpht.
Incorporation of drilling results into the existing 3D geological model indicates a potential kimberlite tonnage of between 28 million tonnes and 34 Mt to a vertical depth of 516 metres. The deposit remains open at depth.
Technical director Jim Davidson said: "Our exploration programme in Botswana has led to the discovery of five new kimberlites so far, and the strong micro diamond results and the favourable coarser diamond size indications for kimberlite KX36 are most encouraging.
“We have now launched the next phase of our evaluation of this exciting discovery, with the bulk sampling work programme scheduled to commence shortly. KX36 is approximately 60 kilometres from the nearest known kimberlite, meaning there is the potential for KX36 to be part of a new kimberlite field," he added.