Asked in Diamonds
What is the difference between a regular diamond and a diamond that is classified as certified diamond?
A certified diamond is one that has been evaluated by a professional in whatever certification method is documented by the certificate. For example, the Gemological Institute of America -- GIA -- certifies diamonds by documenting the colour, clarity, cut and carat weight of the diamond. This establishes the individual characteristics of the gem.
A non-certified diamond can only be evaluated according to the expertise of the person evaluating the diamond, and usually without certification. It's characteristics, therefore, are uncertain.