The company has dropped the guidance by about 10% to 24,500-30,000 carats. That follows the company cutting the guidance by 30% from 36,000-43,000 carats at the start of June.

The 2023 guidance remains unchanged at 43,000 carats.

"The extreme weather conditions, which saw 145mm of rain fall during the Q2 period compared to 9mm of rain for the corresponding period in 2021, are reflected in what is a disappointing quarter with production significantly less than budget," BlueRock executive chairman Mike Houston said.

Production fell 34% year on year in Q2 to 3,570 carats.

"During the period, the company had limited access to fresh kimberlite resulting in the feed to the plant being a lower grade plus having a higher percent of fines/ clay material, which are more susceptible to wet conditions and impacted negatively on throughput tonnage," Houston said.

"As previously report, we have benefitted from improved weather over the past month and a better-balanced drier material has been supplied to the processing plant, taking us one step further towards achieving our stated objective of increasing production to 1 million tonnes per annum," he said.

He said that with the market having remained buoyant for non-Russian rough diamonds, Kareevlei saw an average price of US576 a cart in the quarter, up 35% on the same period last year.  

BluckRock's share price was 8.50p (US$0.11) on 11 July. It has fallen from more than 60p in late March.