Which is the world's largest diamond producing country?

Botswana is the largest diamond producing country in the world in terms of value, leading Russia and South Africa chronologically but in terms of sheer volume of stones, South Africa is still number one, according to most internet searches (and I looked for almost an hour).

As per the "Environmental Literacy Council. Congo is the largest producer of natural diamonds.

According to cheap-diamond.com/countries/ the order is:

1. Russia

2. Botswana

3. Democratic Republic of the Congo

4. Australia

5. South Africa

Zimbabwe is a new country that has come into the fold, they are now apparently the country with the highest concentration for diamonds in the world, Marange!