공시 • Jun 01
Star Diamond Corporation Completes A Study into the Abundance of Type IIa Diamonds in the Trench Cutter Diamond Parcels Recovered from the Early Joli Fou Geological Units At the Star Kimberlite, as Defined by the Star Diamond Geological Model
Star Diamond Corporation announced that the Corporation has completed a study into the abundance of Type IIa diamonds in the Trench Cutter diamond parcels recovered from the Early Joli Fou ("EJF") geological units at the Star Kimberlite, as defined by the Star Diamond geological model. The Star Kimberlite is located within the Fort à la Corne diamond district of central Saskatchewan, Canada (which contains the Star - Orion South Diamond Project), on mineral dispositions held in a joint venture with Rio Tinto Exploration Canada Inc. During 2019, Rio Tinto Canada completed the drilling of ten bulk sample holes (trenches) on the Star Kimberlite using a Trench Cutter Sampling Rig. This study confirms that unusually high proportions of Type IIa diamonds are present in the Star Kimberlite. Of particular note is the exceptionally high proportion of Type IIa diamonds in the larger size fractions of the EJF of which 53% (8 of the 15) of the largest stones, 4 carats and above are Type IIa. This study also confirms and augments earlier studies conducted by Star Diamond of Type IIa diamonds at Star (26.%, +11 DTC (0.32 carats) and above) (see News Releases dated June 09, 2010, March 4, 2019 and May 02, 2022). Type IIa diamonds are very rare and account for less than 2% of all natural rough diamonds mined from kimberlites. Many high-value, top colour, large specials (greater than 10.8 carats) are Type IIa diamonds, which include all ten of the largest known rough diamonds recovered worldwide. The diamonds analyzed represent a spectrum of diamond sizes from +9 DTC (+0.18 carats) through all the large stones, up to diamonds of over 15 carats. The largest Type IIa diamond identified is a 16.96 carat stone. Of note is that nine of these twelve highest value stones are Type IIa. Diamond descriptions and valuations were completed by Mr. Nelson Karun, Diamond Specialist, Saskatchewan Research Council Diamond Services, on behalf of Star Diamond: Only a small number of active diamond mines regularly produce Type IIa diamonds with the most important of these mines being Letseng-la-Terae (Letseng Mine) in the Kingdom of Lesotho and more recently Karowe in Botswana. While Letseng is a low grade (1.5-3 cpht) kimberlite and Karowe has a grade of approximately 15 cpht, they are probably the most prolific source of large high-value Type IIa diamonds, which contribute to making Letseng and Karowe highly economic deposits. Type IIa diamonds contain no nitrogen or boron impurities and are frequently either top white colours (D, E, F or G) or any shade of brown. Many pink and brownish-pink diamonds are also Type IIa. Type IIa diamonds usually have anhedral crystal shape and exhibit a range of elongated, distorted, or irregular morphologies. Most importantly, many high-value, top colour, large specials (greater than 10.8 carats) are Type IIa diamonds, which include all ten of the largest known rough diamonds recovered worldwide, from the 890 carat Incomparable to the 3,106 carat Cullinan. Statistics on the proportions of Type IIa diamonds produced by diamonds mines are not freely available. However, Bowen et al (2009) published Type IIa FTIR measurements for 484 plus two carat diamonds from the Letseng Diamond Mine. The Letseng Mine has a low grade of some 1.5 to 3 cpht but is highly economic as a result of its unusually high average diamond price (USD 2,131 per carat in 2018). Letseng accounts for some 30% of the world market share of diamonds greater than 25 carats and has produced some of the biggest gem quality diamonds recovered in the past number of years including the 910 carat Lesotho Legend, 603 carat Lesotho Promise, the 550 carat Letseng Star, the 493 carat Letseng Legacy and the 478 carat Light of Letseng. These are all Type IIa diamonds. The Karowe Mine of Lucara Diamond Corp. has also produced some record Type IIa diamonds in the past few years, notably 1,758 carat Sewelo, which is the second largest gem diamond ever recovered, the 1,109 carat Lesedi La Rona, which is the third largest gem diamond ever recovered and sold for USD 53 million, and the 813 carat Constellation, which was sold for the record price of USD 63.1 million. Fourier Transform Infrared ("FTIR") Spectrometry is used to determine the concentration and aggregation state of nitrogen within the diamonds using industry standard methods. All analyses of nitrogen content and aggregation state were carried out at the SRC high security diamond facility, with 24-hour video surveillance. The SRC's Geoanalytical Laboratories is accredited to the ISO/IEC 17025 standard by the Standards Council of Canada as a testing laboratory. Star Diamond Corporation is a Canadian based corporation engaged in the acquisition, exploration and development of mineral properties. Shares of the Corporation trade on the TSX Exchange under the trading symbol "DIAM". Star Diamond holds, through a joint venture arrangement with Rio Tinto Canada (a wholly-owned subsidiary of Rio Tinto), a 25% interest in certain Fort à la Corne kimberlites (including the Star – Orion South Diamond Project). These properties are located in central Saskatchewan, in close proximity to established infrastructure, including paved highways and the electrical power grid, which provide significant advantages for future mine development. Rio Tinto refers to their Fort à la Corne mineral properties as "Project FalCon". During 2018, Star Diamond announced the positive results of an independent Preliminary Economic Assessment (the "PEA") on the Project. The PEA (on a 100% basis) estimated that 66 million carats of diamonds could be recovered in a surface mine over a 38-year Project life, with a Net Present Value ("NPV") (7%) of $2.0 billion after tax, an Internal Rate of Return ("IRR") of 19% and an after-tax payback period of 3.4 years after the commencement of diamond production.