Under the ECI programme, Zimbabwean gold producers received a premium to the international gold price. The premium was initially set at 2.5% of gold revenues before rising to 10%.
The withdrawal of the programme is part of the central bank's decision to introduce a new currency, known as RTGS dollars, that can be used to make payments outside Zimbabwe.
The currency is made up of bond notes, coins and all electronic money and is aimed at reducing inflationary pressures in the country.
"At this stage it is unclear whether this policy will address the increasing inflationary pressure in Zimbabwe by creating a transparent and efficient market exchange rate between RTGS dollars and dollars held in FCAs," Caledonia said.
Caledonia said the Reserve Bank of Zimbabwe’s decision to remove the ECI programme would reduce earnings by 40 to 46 US cents per share.
The estimated impact on earnings assumes a gold price of US$1,300 for the rest of the year, the Blanket mine achieving the production guidance of 53,000 to 56,000 ounces of gold and no changes to operating costs.