The foundation that diamond values are based on are the Carat, Colour, Clarity and Cut of a diamond. These are the Four C's of diamond grading and have been the international qualifiers used to define the value of diamonds for centuries. The contemporary diamond industry the world over tried to introduce a fifth C in an attempt to brand diamonds as "certified" or "conflict free". The branding provides added value to the diamonds but the jury is still out on what the Fifth C really is and the court of public opinion will decide this. The value of diamonds is also being re-defined by criminals who have sought out diamonds and like commodities in North America for decades. For criminals, diamonds are seen as instruments to facilitate criminal activity and in this age of money tracking and anti-money laundering legislation, they are also used as a hedge against inflation and the authorities. In the world of criminals who profit from diamonds, the Fifth C is Crime. The Fifth "C": The Criminal Use of Diamonds, exposes why criminals are so drawn to diamonds, how diamonds are used in criminal activity, and why it is difficult to stop this criminal activity.