The Cullinan Mine is owned 74% by Petra Diamonds Limited and is renowned as the source of very rare blue diamonds and large, high quality gem diamonds.
"The last 10 years have been... an exciting time during which we’ve launched lots of industry firsts and helped reimagine the way the sector operates."
The stock fell by 21%, the steepest intraday decline since September, after the miner lowered production forecasts and confirmed that a stronger South African currency would knock annual profits.
The Russian state-controlled diamond miner increased fourth-quarter production by 6 percent year-on-year to 10.1 million carats as a shutdown at its Mir mine was offset by higher output at other assets.