Any traditional process other than cutting and polishing that improves the appearance, durability, or availability of a gemstone
Heating
The use of heat to effect desired alteration of color, clarity, and/or phenomena
Irradiation
The use of neutrons, gamma rays, or beta particles to alter a gemstones color
Diffusion
The use of chemicals in conjunction with high temperatures to produce artificial color change and/or asterism-producing inclusions
Oiling/Resin Infusion
The filling of surface-breaking fissures with colorless oil, wax, resin, or other colorless substances, except glass or plastic, to improve the gemstones appearance
