Coating is the oldest form of diamond treatment. The diamond’s surface is coated, or someone paints colored marks on the diamond pavilion of girdle. Because the diamond is refractive, it spreads the color throughout the diamond. This treatment is not permanent and can be detected under magnification.
Fracture filing is a clarity enhancement that is usually performed on lower clarity diamonds because those diamonds are more susceptible to chipping or breaking during regular wear. When diamonds are fracture filled, the cracks are filled with a glass-like material that appears similar to diamonds and has similar optical properties.
Laser Drill Treatments
Laser drill treatment is when a dark inclusion on a diamond, or carbon spot, is lightened a laser beam targeted on that spot. If a diamond has more than one spot or inclusion, this can be repeated for each one. Laser drill treatments are permanent.
Irradiation is radiation formed from high energy particles; it is used to create color centers in diamonds. Blue and green are likely colors caused by irradiation. The common technique is electron radiation, but in the past diamonds were bombarded with radioactively charged particles from cyclotron generators.
After a diamond goes through irradiation, it sometimes also undergoes annealing. Annealing heats a diamond and can result in modifying the green and blue colors to other colors, such as oranges, yellows, reds, pinks and purples.
Heat Treatment, Graphite Treatment
Heat treatments and graphite treatments are used on diamonds of low quality. They’re heated inside of a vacuum to form graphite deposits in the diamond's fractures, so that the diamonds turn in to black diamonds.
High Pressure High Temperature
A diamond is given high pressure high temperature treatment if it is a minor class of Type II A or Type IaB. These diamonds are brown and exposed to pressures of 70,000 atmospheres and temperatures of 2,000 degrees Celsius. This causes the diamonds to turn white or another color other than brown.