Why are stolen diamonds easy to resell without being traced?

Every diamond is unique -- just like every human -- but few diamonds are documented and appraised, which makes them easier to identify. Each has its own carat weight, colour, cut and clarity.

Also, people who buy diamonds are not always rigorous about checking the identity of a stone before buying it.

If you own a diamond, you can buy an appraisal, which describes the stone with precision and includes a photograph. Then buy insurance to cover the replacement value of the stone. Best practices dictate that this is most common for stones in excess of one carat.