Firestone Diamonds said its output fell in the second quarter, though it stuck to its annual production guidance.
The company, which mines gems at its Liqhobong mine in Lesotho, said it recovered 224,947 carats in the three months through December, down from 240,733 carats in the first quarter.
Less ore was treated in the second quarter due to unscheduled repair work on scrubber.
The company nevertheless stuck to its annual output guidance of between 820,000 and 870,000 carats.
A total of 191,735 carats were sold in the second quarter, realising revenue of $13.9m up from $13.5m in the first quarter.
Cost during the quarter of $12.00 per tonne treated and $10.96 year-to-date were substantially lower than annual guidance of US$15-16 per tonne.
'We had a reasonable second quarter, barring a scrubber failure sustained in November, ending the financial half year with all our production parameters on track to meet guidance by year end,' chief executive Paul Bosma said.
'The demand for the smaller, lower value stones deteriorated further during the quarter albeit that it stabilised at the December sale and remained at the same level for the January sale.'
'Pleasingly the demand for larger, better quality stones remains strong as was evidenced by the pricing received for the 46 carat white stone that was sold during the first sale of 2019.'
At 2:38pm: (LON:FDI) Firestone Diamonds PLC share price was -0.25p at 2.63p