The investment includes a $2.4-million term loan and a $1.6-million convertible debenture.
Diamcor is developing the Krone-Endora at Venetia project in South African that it acquired from De Beers Consolidated Mines Ltd. in 2011.
The company plans to use the money to buy equipment and expand its current in-field screening operations.
Diamcor signed a deal with Tiffany & Co. last year that gave the jeweller the first right of refusal for up to 100 per cent of the production of rough diamonds from Krone-Endora at Venetia, excluding individual stones of 10.8 carats or greater.
Under that agreement, Tiffany & Co. invested $5.5 million in the company, including a $3.5 million term loan and a $2 million convertible debenture.