Any unnatural process that alters the appearance, particularly the Color or Clarity, of a natural diamond. Coating, irradiation, high temperature/high pressure, fracture filling and Laser Drilling are all examples of enhancements. Most of these are covered in my Diamond Scams tutorial. Some say the only acceptable enhancements are cutting and polishing. I will also accept laser drilling, since it is permanent, and duly noted on grading reports from the labs. And I am also lenient about HPHT, since it is permanent, as long as it is disclosed. Most other treatments are not permanent.
Synonymous with “treatment.”