These are treatments that are performed on pure diamonds in order to improve on their gemological visual features in different ways. These treatments are very important when it comes to altering the visual look of diamond and they include features such as clarification treatments which might involve drilling the diamond using laser in order to be able to remove inclusions of black carbons which are attached to the diamond.
According to Speedy Diamond, a diamond can also be taken through fracture filling in order to make any cracks that might be existing to be invisible to the person who is to buy or use it, irradiation of the diamond color and treatments involving annealing can be done on the diamond. annealing and color irradiation helps in making the diamonds which are usually brown and yellow to have a vibrant color. Most states requires that one discloses all the treatments that has been made of the diamond during the time of sale and this is important since one is able to discover whether what they want is their best choice. Some of the treatments given to diamond might be very controversial and even affect some of the unique features of diamond. The sale of diamonds depends on how pure it is, the one which is pure and natural can be sold at better prices than the one which has impurities added on it. This happens because people believe that those diamonds that are treated have low quality and hence enhancement is done so as to improve on the quality, making these diamonds to have substandard prices.
Usually after diamond is taken through the enhancement process, it appears visually good than the one which has not been enhanced, this makes all the treated diamonds to appear as if they have a greater value than those which are not treated but the fact remains that those which are not treated are the ones that have a greater value. One can get the details of how to enhance diamond from wikipedia where all the steps are explained. Check it out, a lots of good info on the following topics can be found here