Second only to Christmas, Valentine's Day is the holiday when diamonds are most often given as the ultimate token of love. Central to the diamond's role as a romantic symbol is the belief that diamonds are one of the rarest, most precious gifts for a loved one. But it's only a myth--diamonds are found in plentiful supply. FRONTLINE examines how the great myth about the scarcity of diamonds and their inflated value was created and maintained over the decades by the diamond cartel. This report chronicles how one family, the Oppenheimers of South Africa, gained control of the supply, marketing, and pricing of the world's diamonds.