Final answer:
The article's main idea revolves around the discovery of a significant diamond and the consequential impact on South Africa's mineral wealth and social landscape, particularly highlighting the role of DeBeers in the diamond industry.
Step-by-step explanation:
The main idea of the article is c. The discovery of a large diamond and its impact on South Africa's mineral wealth. This is evident from the excerpts that describe the astounding discovery of a large and perfect diamond, hinting at significant mineral wealth, and link to the economic and social implications of such a find. Additionally, the text touches upon the role of companies such as DeBeers in controlling a large portion of the diamond production, which has directly affected countries like South Africa, Angola, and Namibia, the exploitation of natural resources, and the term 'blood diamonds' associated with the financing of military conflicts through diamond sales. These points collectively underline the profound effect of diamond discovery and trade on South Africa's wealth and socio-political landscape.