Diamond enhancements, frequently referred to as "treatments," are various ways of improving the characteristics of diamonds that are already cut and polished. Diamonds are treated to improve such qualities as clarity so that they can be sold at higher prices.
The United States Federal Trade Commission requires jewelers to clearly disclose all treatments done on every diamond. Treated diamonds rank lower on the quality scale when compared to untreated or "natural" diamonds, so they are usually sold at substantial discounts. The consensus in the jewelry industry is that you should consider buying only 100% natural diamonds if you want high quality.
Here are some of the treatments that jewelers use to artificially enhance the quality of diamonds.
Bleaching Bleaching can take an otherwise dull-looking gemstone and bring it to the point where its clarity approaches the brightness of a colorless or near colorless diamond.
Heating A diamond is heated to a high temperature to improve the gem's clarity and/or color.
Irradiation Diamonds are bombarded with neutrons to make them more colorless. Sometimes these irradiated gems are then heat treated to further enhance the diamond's color.
Gamma/Electron Irradiation With this treatment, diamonds are exposed to gamma rays or are bombarded with electrons to change the diamond's color quality.
Infilling/Fracture Filling For a number of reasons, many diamonds have cracks on their surfaces and those cracks can be "filled" with material like plastic or glass. A secondary reason to use this treatment is to strengthen the gemstone, making it more durable. Any professional gemologist can spot these fillings by observing how the light behaves within the stone.
Laser treatment A laser is used for treatment of diamonds that have some inclusions that lower its quality. Most often this treatment is used when diamonds have visible black inclusions.
Oiling/Resin Infusion With this technique a diamond's surface cavities are filled with colorless materials such as paraffin, resin, oil or wax. The intent is to improve its appearance.