What are Nombeko's diamonds?

Taken from the dead man Thabo in the first chapter of the novel, Nombeko sews a handful of raw diamonds into the lining of her jacket at the age of 14. They are an insurance policy for her, and yet also a danger, because nobody would believe a black girl would come by such wealth honestly. The diamonds are a comfort for her for two decades, always an option, until she is finally able to sell them in Sweden, years later.