JOHANNESBURG (miningweekly.com) – Aim-listed Paragon Diamonds on Monday said it had increased the plant processing rate at its Lesotho-based Lemphane kimberlite project bulk-sampling programme to over 230 t/d.

The company indicated that it had also completed the processing of two additional kimberlite samples of 3 371 t and 1 201 t. This followed the successful installation of a water-supply pipeline at the site.

P5, the 3 371 t sample, yielded an 8.86 ct yellow dodecahedron, the largest diamond at Lemphane, to date, with MD Stephen Grimmer indicating that the stone represented 5% of the value of the total carats recovered at the project thus far.

The same sample also produced four other diamonds above 1 ct for a total of 35.35 ct at a grade of 1.24 carats per hundred tonnes (cpht). However, this excluded diamonds that could still be recovered, therefore, the grade could increase marginally.

To date, Paragon had processed 14 401 t of a planned total 35 000 t and had recovered 201.79 ct, for an average recovered sample grade of 1.62 cpht. Grimmer noted that over more than one-third of all carats recovered to date were diamonds of 1 ct or greater.

Sampling results reflected a coarse diamond size distribution with an average diamond size of between 0.23 ct per diamond and 0.41 ct per diamond and some 36% of diamonds above 1 ct in size. In total, 31 diamonds over 1 ct and ten diamonds over 2 ct in size had been recovered to date.

"The largest stone recovered to date helps confirm our view of Lemphane as a potential large-diamond producer. It clearly shows that, with increased sampling, further and larger diamonds should be forthcoming in line with statistical projections.

“We also expect improvement in the grade as sampling increases. The recovery of a single large stone can have a disproportionately positive effect on the total carats and, thus, on the grade, as has already been demonstrated," Grimmer stated.