The Black Diamond is the sixth book in the saga. This time Juan is born in Lesotho, South Africa. As his immortal spirit continues to live on, he is able to vividly recall his eternal past and cannot understand why whites despise men of his race. His father Moshoeshoei, king of the Basotho, instructs him in the art of government and in the subtleties of diplomacy. His mother, offspring of Chaka Zulu, wants to end her people's suffering and wishes that his son will dedicate his life to save their bodies and spirits. The protagonist's principle desire is the same as that of all his other lives - to find the woman that was created with him at the beginning of time. Maluti and Tineke sense each other's existence and recognize that they are a couple of kindred spirits who prowl about the world in search of love; but they never meet.

The novel takes place during a difficult time in Africa. Gold and diamonds are discovered. The descendants of the Dutch struggled to rise from the tyranny of England as the blacks fight to preserve their homeland. The British Empire, which is under the auspices of a brotherhood, appears to be unbeatable as it is filled wealth of the seven continents, usurping the natural resources in the seas by attacking ships of Spain, Holland, China and India. After centuries of ideological conflicts and social, religious and political differences, the nations distance themselves. The weapons become more sophisticated and, although the science improves, diseases decimate men and animals. Gradually the planet is invaded by the human species that threatens to destroy everything in its path, including a variety of almost extinct birds, fish, reptiles and mammals.

The author take us back to that time in the black continent where misery was sown to reap riches, which despised the colored races and where slavery was accepted as natural by masters and servants. By hearing their stories we suffer with the author with the wars of suppression of the descendants of the Dutch by the English forces. We appreciate the martyrdom of children and women who died in concentration camps. We feel in our own skin the suffering of blacks, who were martyred in the mines of gold and diamonds. We mourn with him to read the stories of those who die of plague and famine after its members are amputees and we suffer with him in the Congo for the genocide of humans and elephants.