Precious stones miner Gemfields Plc reported a sharp fall in third-quarter production as high unseasonal rainfall in Zambia hurt output from its core Kagem mine.
Production fell about 45 percent to 3.6 million carats of emerald and beryl for the quarter ended March 31.

Gemfields, which produces about a fifth of the world's rough emeralds, reported grade of 198 carats per tonne in the third quarter compared with 265 carats per tonne a year earlier.

However, Gemfields said it expected an improvement in grades at Kagem and overall production volumes in line with its expectations.

The London-listed miner has long held ambitions of creating a stable world market for emeralds and polishing the gem's image in the same way that Anglo American Plc-owned De Beers championed diamonds from London's Bond Street to China.

The company said its luxury brand Fabergé reported a 134 percent jump sales and sales orders agreed during the quarter.

Gemfields' first ruby auction is scheduled to take place in Singapore in mid June.

"(It was) a difficult quarter operationally for Gemfields although this is no surprise given the weather issues compounded by the inherent variability of gemstone mining, which is characterised by grade and ore variability," analysts at Numis Securities wrote in a note.

Gemfields shares were down 4.4 percent at 38.00 pence in early trading on the London Stock Exchange on Friday.