IFC, a member of the World Bank Group, was an anchor investor in the sale that raised $300m in total.
Proceeds from the notes will enable Petra to construct a new processing facility at Cullinan mine.
IFC had earlier provided a $40m loan to Petra Diamonds to support the expansion of the Williamson diamond mine in Tanzania.
IFC global head of mining Namrata Thapar said: "We are committed to supporting Petra as it develops and optimizes its operations in South Africa in a sustainable way.
"We hope the successful bond issuance opens the door to more diversified financing sources for the mining sector."
Cullinan mine is claimed to be the world’s only significant source of rare blue diamonds. The 3,106-carat gem diamond was discovered at the facility in 1905.
The mining sector contributes around 18% of South Africa’s gross domestic product and more than 50% of the country’s foreign exchange earnings.
