A Zimbabwean research agency predicts that the global supply of rough diamonds will increase by ten to fifteen million carats in the years to come, but that this increase will consist of lower value stones, Rough and Polished reports.

In its 2013 Diamond Report, Equity Communications noted that major infrastructural work had been completed at diamond projects in Zimbabwe and at projects owned by mining giant Rio Tinto. As a result of these upgrades, the diamond industry will see a surge in the production of low-grade rough diamonds, for a period of five years, lasting from 2014 to 2018.

The firm also noted that the average per carat value of global annual diamond production dropped in 2012, and that it was only the second time that had happened in the decade that preceded it, according to Rough and Polished. Equity predicted that the average per carat value would jump by 5% this year to hit $103.81.