AGTA Enhancement Codes
American Gem Trade Association (AGTA) Enhancement Codes
ENHANCEMENT: Any treatment process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.
N: The “N” symbol appears on the chart only for natural stones which are not currently known to be enhanced; however, the “N” symbol can also be used for other natural gemstones in the event that a stone has received no enhancement and the seller will provide a guarantee that there has been none.
E: The “E” symbol indicates that a gemstone has undergone its traditional enhancement process.
SYMBOLS FOR SPECIFIC FORMS OF ENHANCEMENT
B: BLEACHING
The use of heat, light and/or other agents to lighten or remove a gemstone's color.
C: COATING
The use of such surface enhancements as laquering, 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 present color or improve color uniformity.
F: FILLING
The filling of surface-breaking cavities or fissures with colorless glass, plastic, solidified borax or similar substances, which are visible under properly illuminated 10X magnification. This process will improve durability, appearance, and/or add weight.
H: HEATING
The use of heat to effect desired alteration of color, clarity, and/or phenomena (Residue of foreign substances in open fractures is not visible under properly illuminated 10X magnification).
HP: HEAT & PRESSURE
The use of heat and pressure combined to effect desired alterations of color and/or clarity.
I: IMPREGNATION
The impregnation of a porous gemstone with a colorless agent (usually plastic) to give it durability and improve appearance.
L: LASERING
The use of a laser and chemicals to reach and alter inclusions in diamonds.
O: 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 gemstone’s appearance.
R: IRRADIATION
The use of neutrons requiring an environmental safety release from the Nuclear Regulatory Commission (NRC), Gamma 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 temperatures to produce color and/or asterism-producing inclusions.
W: WAXING/OILING
The impregnation of a colorless wax, paraffin, and oil in porous opaque or transluscent gemstones to improve appearance.
OTHER ENHANCEMENT CODES
SYN: SYNTHETIC
The reproduction of natural gems with essentially the same composition and structure as their natural counterparts.
ASBL: ASSEMBLED
The process of producing a single stone from two or more separate pieces.
ENHANCEMENT: Any treatment process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.
N: The “N” symbol appears on the chart only for natural stones which are not currently known to be enhanced; however, the “N” symbol can also be used for other natural gemstones in the event that a stone has received no enhancement and the seller will provide a guarantee that there has been none.
E: The “E” symbol indicates that a gemstone has undergone its traditional enhancement process.
SYMBOLS FOR SPECIFIC FORMS OF ENHANCEMENT
B: BLEACHING
The use of heat, light and/or other agents to lighten or remove a gemstone's color.
C: COATING
The use of such surface enhancements as laquering, 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 present color or improve color uniformity.
F: FILLING
The filling of surface-breaking cavities or fissures with colorless glass, plastic, solidified borax or similar substances, which are visible under properly illuminated 10X magnification. This process will improve durability, appearance, and/or add weight.
H: HEATING
The use of heat to effect desired alteration of color, clarity, and/or phenomena (Residue of foreign substances in open fractures is not visible under properly illuminated 10X magnification).
HP: HEAT & PRESSURE
The use of heat and pressure combined to effect desired alterations of color and/or clarity.
I: IMPREGNATION
The impregnation of a porous gemstone with a colorless agent (usually plastic) to give it durability and improve appearance.
L: LASERING
The use of a laser and chemicals to reach and alter inclusions in diamonds.
O: 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 gemstone’s appearance.
R: IRRADIATION
The use of neutrons requiring an environmental safety release from the Nuclear Regulatory Commission (NRC), Gamma 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 temperatures to produce color and/or asterism-producing inclusions.
W: WAXING/OILING
The impregnation of a colorless wax, paraffin, and oil in porous opaque or transluscent gemstones to improve appearance.
OTHER ENHANCEMENT CODES
SYN: SYNTHETIC
The reproduction of natural gems with essentially the same composition and structure as their natural counterparts.
ASBL: ASSEMBLED
The process of producing a single stone from two or more separate pieces.