2007 DO-27 Bulk Sample Results Confirm Grade of Main Lobe at 0.89 Carats/Tonne, 1,724.57 Carats of Diamonds Recovered, Including Fancy Yellow Gems

September 18, 2007 PDF version
Vancouver, British Columbia, Canada — Tuesday, September 18, 2007 — Peregrine Diamonds Ltd. (TSX-PGD) (“Peregrine”) today announced the results of the 2007 bulk sample from the nine hectare DO-27 kimberlite pipe, WO Diamond Project, NT, Canada.

The 2007 bulk sample average modelled grade for the Main Lobe pyroclastic kimberlite (PK) is 0.89 carats per tonne (89.13 carats per hundred dry tonnes), confirming Peregrine’s previous bulk sample estimates of 0.90 carats per tonne in 2005 and 0.88 carats per tonne in 2006. This Main Lobe PK lithology represents at least 80% of the DO-27 kimberlite complex.

In total, 18,371 diamonds greater than +1 DTC sieve size (approximately +1.1 millimeter), comprising 1,724.57 carats, with an average stone size of 0.094 carats per stone, were recovered from approximately 2,520 dry tonnes of kimberlite from all lithologies in the Main and Northeast Lobes of DO-27 in the 2007 bulk sample.

The twenty largest diamonds recovered in 2007 are 9.45, 7.03, 6.03, 5.17, 4.84, 4.35, 4.19, 3.62, 3.48, 3.38, 3.23, 3.18, 3.12, 3.08, 3.03, 2.86, 2.82, 2.67, 2.53, and 2.48 carats, with twelve of these stones being gem or near gem-quality. Of particular interest is the recovery of fancy yellow gem-quality diamonds, including a very high quality, 4.35 carat stone. This is the first occurrence of fancy coloured gems being recovered from DO-27.

The 2007 bulk sample tonnage was obtained from 28 large diameter (24”-28”) drill holes (LDD) completed to a maximum depth of 295 meters below surface. Extracted kimberlite tonnage estimates were calculated using a down-hole caliper and a three-dimensional density model of the various kimberlitic lithologies prepared by AMEC Americas Ltd. As some of the LDD holes were drilled to achieve maximum kimberlite volume extraction, these particular holes were not suitable for tonnage estimation and grade calculations and therefore have been omitted from those calculations; however, all recovered diamonds can and will be used for diamond valuation.

Since different sizes and types of bottom size screens were used in the 2005, 2006 and 2007 bulk sample drilling and processing, all grade results were normalized to a uniform datum of a 1.0-millimeter bottom screen size for the 2006 bulk sample results and a 1.4-millimeter bottom screen size for the 2007 bulk sample results, and then modelled. This procedure is in accordance with industry standard practice when calculating diamond grades from multiple bulk samples that have different bottom screen size data sets. The 2005 bulk sample was not suitable for modelling due to its small size relative to the 2006 and 2007 bulk samples.

The individual and combined 2006 and 2007 bulk sample normalized grades for the Main Lobe and Northeast Lobe PK, using LDD holes drilled for grade calculations, are summarized below:

2006 AND 2007 NORMALIZED GRADES
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Year         Lithology       Tonnes    Carats   CPHT(i)
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2006         Main Lobe PK    332.80    296.55    89.11
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2006         NE Lobe PK       20.05     14.81    73.87
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2007         Main Lobe PK   1616.01   1440.34    89.13
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2007         NE Lobe PK      322.86    253.05    78.38
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Combined     Main Lobe PK   1948.81   1736.89    89.13
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Combined     NE Lobe PK      342.91    267.86    78.11
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2006         Main + NE PK    352.85    311.36    88.2