Natural Gemstones Enhancements Table

Natural Gemstones Enhancements
"Enhancement" - any traditional process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability or availability of a gemstone.

Not Enhanced (N)
The “N” symbol is used on our website to indicate:
gemstones that are not currently known to be enhanced (alexandrite, some garnets, etc.) or
gemstones where it can be proved (via gemological or other means) that a gem has not been subjected to any enhancement.
Normally Enhanced (E)
The “E” symbol indicates that the gemstone has undergone its traditional enhancement process. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, our approach is to assume that such enhancements have been done to that particular gemstone.

Symbols For Specific Forms of Enhancement

B = Bleaching: The use of heat, light and/or chemicals or other agents to lighten or remove a gemstone's color.
C = Coating: The use of such surface enhancements as lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, provide color or add other special effects.
D = Dyeing: The introduction of coloring matter into a gemstone to give it new color, intensify existing color or improve color uniformity.
F = Filling: The filling of surface breaking cavities or fissures with colorless glass, plastic, or some similar substance. This process will improve durability, appearance and/or add weight.
H = Heating: The use of heat to alter color, clarity, and/or phenomena. For ruby, "Heat" signifies heat only or possibly heat with minor fissure healing, a permanent process.
HP = Heating and Pressure: The use of heat and pressure combined to effect desired alterations of color, clarity and/or phenomena.
I = Impregnation: The impregnation of a porous gemstone with a colorless agent (usually plastic) to improve durability and appearance.
L = Lasering: The use of a laser and chemicals to reach and alter inclusions, usually diamonds.
O = Oiling/Resin Infusion: The filling of surface-breaking fissures with a colorless oil, wax, resin or other colorless substances, except glass or plastic, to improve the gemstone’s appearance.
R = Irradiation: The use of neutrons, gamma, ultraviolet and/or electron bombardment to alter a gemstone’s color. The irradiation may be followed by a heating process.
U = Diffusion: The use of chemicals in conjunction with high-temperature heat treatment to produce color change and/or asterism-producing inclusions.

W = Waxing/Oiling: The impregnation of a colorless wax, paraffin and/or oil in porous or translucent gemstones to improve appearance.