The Orion South diamond project, in central Saskatchewan, has been confirmed to contain a high proportion of rare type diamonds – Type IIa – which account for less than 2% of all natural diamonds mined from kimberlites.
A recent study has confirmed that “unusually high” proportions of Type IIa diamonds are present in the Star (26.5%) and Orion South (12.5%) kimberlites, Star Diamond Corporation reported on Monday.
Only a small number of active mines regularly produce Type IIa diamonds, with the most prominent one being the Letseng mine, in Lesotho. Although Letseng has a low grade kimberlite, it is one of the most prolific sources of large high-value Type IIa diamonds.
A 2010 study on plus 2.7 ct diamonds from Star demonstrates that the Star kimberlite has a similar proportion of Type IIa diamonds to Letseng, Star Diamond reported.
The company stated that, in its latest study, it had analysed a spectrum of diamond sizes from +11 DTC (+0.32 ct) through all of the large stones, up to diamonds of nearly 50 ct. The largest Type IIa diamonds identified include a 49.09 ct stone from Star and a 32.35 ct stone from Orion South. The most valuable of the Type IIa diamonds from Star is the 11.96 ct diamond valued at $11 333/ct and the most valuable of the Type IIa diamonds from Orion South is the 15.88 ct diamond valued at $2 800/ct.