In this latest update, the AIM listed group said 1,182 carats had been recovered, taking the average grade to a better than anticipated 178.7 carats per hundred tonnes (cpht).
This is 49% higher than the 120 cpht applied in the resource estimate and represents a decent advance on the 155 cpht logged in July.
Stellar said 53 diamonds were larger than one carat, including stones of 6.7 and 4.6 carats as it revealed they were of “excellent shape, colour and clarity”.
Chief executive Karl Smithson said: "Tongo continues to generate excellent results further underpinning the economic potential of this kimberlite diamond project.
“We have achieved our objective of collecting a further 1,000 carat parcel for the diamond grade and valuation modelling of Tongo Dyke 1, as part of the ongoing feasibility work.
“It is highly encouraging to note the substantial increase in grade to 179cpht which has resulted from reprocessing the tailing material.”