UK-based Stellar Diamonds has discovered high-grade and exceptional quality diamonds at its Dyke-1 of Tongo project in eastern Sierra Leone.
The company has so far recovered 551.6ct from its bulk sampling programme at an average grade of 126.3ct per hundred tones (cpht), which is higher than the estimated grade of 120cpht.
A number of outstanding gem-quality diamonds have been uncovered with stones up to 6.7ct in size.
Stellar noted that the grade will increase as further diamonds are recovered from re-processing.
The bulk sampling of the 1.1 million carat Tongo dyke is part of the definitive feasibility study (DFS) conducted by the company, which is on track for completion by the end of the year.
Stellar Diamonds chief executive Karl Smithson said the results from the on-going bulk sampling programme continue to underscore the Tongo Dyke-1 kimberlite’s high-grade nature.
"The presence of larger gem stones up to 6.7ct in size bodes well for the diamond valuation, which will be undertaken as part of the DFS that is on-track for delivery towards the end of 2014," Smithson said.
The company’s sampling programme is expected to continue, so as to recover at least 1,000ct for diamond grade and value modelling on the existing JORC-compliant resource.
Stellar is undertaking bulk sampling at Dyke-1 as part of the DFS.
Based on the location of the kimberlite, the sample can be broadly divided into sub-samples.
The company collected sample nine, which comprised fresh and hard kimberlite, through drilling and blasting of a 33m section of the kimberlite to a depth of up to 17m. Sample ten was collected using an excavator over 77m of strike and to a depth of about 3m, to the west of sample nine and closer to surface, where the kimberlite and surrounding rock was heavily decomposed.