Sierra Eye: Petra Diamonds Ld

Petra Diamonds Limited ('Petra') announces an update concerning the Kono diamond project in Sierra Leone. Petra's interest in the Kono project is 51%, with its joint venture partner Stellar Diamonds Limited ('Stellar'), a 68.5% owned subsidiary of Mano River Resources Inc (AIM: MANA, TSX-V: MNO), holding the remaining 49%. Highlights * The development programme makes further solid progress, with test shafts delivering highly encouraging results * Trial mining commenced on three shafts where in-situ grades of between 50 and 80 carats per hundred tonnes ('cpht') have been achieved * Petra believes that the test shafts have a high likelihood of developing into economic production operations * 2,809 diamonds totaling 241.7 carats recovered from trial mining to date (February 2007: 638 diamonds, 58.8 carats) * The increase in diamond recoveries is due to the better quality kimberlite now encountered, more consistent kimberlite fissure and better fissure widths; all very positive signs for the future development of economic operations Adonis Pouroulis, Chairman of Petra, commented; 'We are pleased to report the further positive progress at the Kono project. The trial mining is going well and whilst further work is required in order to infer a representative grade and value, the results to date support our expectations for the Kono project and we progress with confidence into the next phase of the development. The quality, consistency and width of the kimberlite now encountered are all positive signs for the future development of economic operations.' Stellar's CEO, Karl Smithson, commented: 'We are very encouraged by the news given by Petra Diamonds from the Kono operations. We would like to commend Petra, our partners, on their diligent and effective management of the project. Petra is the world leader in underground kimberlite fissure mining and they have assembled a first class operational team that we are confident can bring success to the Kono project.' Test Shaft Development The development programme at Kono has achieved some highly encouraging results in recent months with potentially economically viable kimberlite fissures having been opened. Diamond yields, fissure widths and the underground mining and geological conditions have enabled Petra to concentrate test shaft efforts on three very promising diamondiferous kimberlite fissure targets. To date five shafts have been sunk, each to a depth of 30 metres. Three of these shafts are now at the trial mining stage on the 30 metre level and have been returning satisfactory in-situ kimberlite grades of between 50 and 80 cpht. These shafts display a consistent, near-vertical dipping fissure line with very encouraging in-situ shaft sinking grades; fissure widths vary between 40 centimetres ('cm') and 200cm with satisfactory mining conditions experienced to date. Two shafts were discontinued because diamond recoveries during the shaft sinking and trial mining phases did not match the potential of the other three shafts. The test shafts are at advanced levels of development and the processing of the limited amount of weathered, diluted and mixed diamondiferous kimberlitic material extracted during shaft sinking has yielded 2,809 diamonds totaling 241.7 carats. The ten largest diamonds ranged in size from 0.65 carats to 7.2 carats. Although the diamond yields are highly encouraging from the small amount of material processed, Petra is of the opinion that the scale of the test work conducted is presently too limited to arrive at any representative grade or value and accordingly will report on further findings when available. The next phase of the project will excavate approximately 100 metres of kimberlite along strike of ore body at each shaft, so as to process approximately 1,000 tonnes of clean kimberlite and obtain acceptable run of mine grades and diamond values to be used in proposed business plans. It is anticipated that this next phase programme will be completed by March 2008. Exploration Development During shaft sinking operations Petra found that, due to the highly saprolitised nature of the rocks in this locality, the silicate and spinel kimberlite indicator minerals have been destroyed, in many cases to depths of up to 20 metres. It has further been ascertained that ilmenite-deficient kimberlites exist in the area. These conditions may mean that kimberlite pipes were overlooked during mining and exploration operations carried out by previous operators in the area. Petra is therefore considering the flying of a low-level helicopter borne electro-magnetic survey over the licence areas so as to prospect for these potential deposits.