Enhancements
| Gemstone Enhancement Codes (based on AGTA guidelines) | |
| B
Bleaching |
The use of heat, light and/or chemicals or other agents to lighten or remove a gemstone’s color. This is often accompanied by subsequent dying and/or impregnation. Example: bleached cultured pearl; bleached/impregnated jadeite |
| 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. Example: coated diamond, coated topaz (mystic topaz) |
| D
Dyeing (Staining) |
The introduction of coloring matter into a gemstone to give it new color, intensify existing color or improve color uniformity. Example: dyed green jadeite |
| E
Normally Enhanced |
The “E” symbol is used for gemstones that are routinely enhanced. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, our approach is to assume that such enhancements have been applied to that particular gemstone. This assumption is made to protect both buyer and seller. If a more specific method of enhancement is known, then the specific enhancement code will be used. |
| 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 weight. Example: ruby |
| FH
Flux healing |
During heat enhancement, fluxes (or heat alone) may be used to heal fractures/fissures which were formerly open. The process dissolves the walls of the fractures and redeposits the molten gem material, healing the fractures closed. Example: ruby (particularly that from Mong Hsu, Burma) |
| H
Heating |
The use of heat to alter color, clarity, and/or phenomena. Example: Ruby, sapphire, tanzanite, aquamarine, demantoid garnet |
| HP
Heating & Pressure |
The use of heat and pressure combined to affect 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. Example: Stabilized turquoise. |
| L
Lasering |
The use of a laser and chemicals to reach and alter inclusions. Example: diamond |
| N
Not Enhanced |
The “N” symbol is used to indicate one of two situations. First, there are certain gemstones that are not currently known to be enhanced (alexandrite, some garnets, etc.) Second the “N” symbol may also be used for a gem where it can be proved via gemological or other means that a gem has not been subjected to any enhancement. |
| 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. Example: emerald |
| 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. Example: Blue topaz, colored diamonds |
| U
Lattice |
Outside-in diffusion of coloring chemicals via high-temperature heat treatment to produce color and/or asterism. Example: lattice diffusion-treated sapphire |
| W
Waxing/Oiling |
The impregnation of a colorless wax; paraffin and/or oil in porous gemstones to improve appearance. Example: jadeite |
