Gemfields PLC (LON:GEM) produced 4.7 mln carats of emerald and beryl at an average grade of 156 carats per tonne during the quarter to December 2016.
That was down on the corresponding quarter in 2015, as the company mined through a lower grade zone at its Kagem emerald mine in Zambia.
A reduction in operating costs partially off-set the production drop though, down by nearly US$2 mln at US$10.2 mln.
Meanwhile, over at the company’s ruby mine in Mozambique, production rang in at 1.1 mln carats of ruby and corundum.
The company said that a mixed ruby and corundum auction held in Singapore in mid-December generated revenues of US$30.5 mln at an average of US$27.88 per carat.
The next emerald auction will be held in February in Lusaka.