According to Nelson Mandela, the greatest wealth of his country was its people. He believed that while South Africa was rich in minerals and gems like diamonds, the real and greatest wealth lay in the people of the nation. Mandela emphasized that people are finer and truer than the purest diamonds, and their resilience, skills, and spirit were the driving force behind the country's progress and the end of apartheid. This highlights the value of human capital over material wealth in building a nation's strength and future.