UNITED Kingdom-based global mining group Rio Tinto's share of production in Zimbabwean mine Murowa Diamonds has slid 24% in the third quarter of 2013, compared to the same period last year, to 70 000 carats, the group said.

In its 2013 third quarter production update Rio Tinto, which has listings on the London, New York and Australian stock exchanges said the company's share of production at the Zvishavane mine had grown by 1% in the first nine months of the year to 217 000 carats, from 215 000 carats in the same period in 2012.

Rio Tinto recorded a 12% year-on-year growth in diamond production to 4 158 million carats for the third quarter to September 30 compared to 3 706 million carats in the previous comparative period. In the nine months of the year, the group's output grew 17% in 2013 to 11 529 million carats.

The company said growth in production was mainly driven by an increase in the amount of ore processed and higher-grades at its fully-owned Argyle mine in western Australia, following full commissioning of the underground mine in April 2013.

Argyle mine produced 3,1 million carats in the third quarter of 2013, up 26% from the same period last year. In the nine months under review, the mine's production went up 27% year-on-year to 8,2 million carats.

Rio Tinto's production at the Canada-based Diavik mine, in which it owns a 60% stake, fell 13% to 1,003 million carats due to lower grades of ore mined during the quarter.

In June this year, Rio Tinto said it was reversing its initial decision to dispose of its diamond operations after the market failed to meet its asking price. The move disappointed seven potential suitors who had been linked to the takeover of part of or the entire Rio Tinto stake in Murowa.