AGTA Treatment Codes
N
Not Enhanced
B
Bleaching
C
Coating
D
Dyeing
F
Filling
H
Heating
HP
Heat and Pressure
I
Impregnation
L
Lasering
O
Oiling/Resin
R
Radiation
U
Diffusion
SC
Special Care
ASBL
Assembled
CMP
Composite
W
Waxing/Oiling (Opaque Stones)
To learn more about specific gems and common industry treatments, visit the AGTA Website here
"Genuine," in the industry, refers to gems that are Earth-made, which may have undergone certain treatments to enhance their natural beauty.
Some common, industry-accepted treatments include, but are not limited to:
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Heating sapphires and rubies to improve their appearance, unless specified otherwise.
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Oiling emeralds to enhance their clarity, unless noted differently.
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Heating tanzanites to achieve their deep blue color.
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Bleaching pearls to brighten their appearance.
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Radiating or heating topaz to bring out its color.
These treatments are typically applied early in the supply chain and are considered stable. When properly disclosed, they generally do not compromise the gem’s integrity or value. As standard practice in the gemstone industry, these treatments help jewelers create stunning, high-quality pieces at accessible prices while ensuring transparency and quality craftsmanship.
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Learn more about about gem treatments at our blog here.
GEMSTONE | TAG CODE | ENHANCEMENT METHOD | FREQUENCY USED | STABILITY | CARE REQUIRED | SPECIAL ADVICE |
|---|---|---|---|---|---|---|
Alexandrite | N | None | Normal | |||
Amazonite | W | Impregnated with a colorless wax,paraffin or oil to improve appearance | Usually | Good to Fair | Special Care | Avoid heat, chemicals and ultrasonic |
I | Impregnated with plastic and other hardened resins to improve appearance | Usually | Very Good | Special Care | Avoid chemicals and ultrasonic | |
D | Dyed or surface treated to add color | Occasionally | Fair | Special Care | ||
Amber | H | Heated to improve appearance and "sun spangles," or deepen color | Usually | Very Good to Good | Special Care | Avoid chemicals and ultrasonic |
D | Dyed or surface treated to add color | Rarely | Variable | Special Care | Color fades, avoid heat and extended sun | |
HP | Changed color and/or artificially aged, treated in autoclave | Commonly | Very Good | Normal | Avoid chemicals and ultrasonic | |
Amblygonite | R | Irradiated to improve colors | Occasionally | Special Care | Color fades, avoid heat and chemicals | |
Amethyst | H | Heated to lighten color and/or to remove "smokey" components | Occasionally | Excellent | Special Care | Some unheated material may fade in long exposure to sunlight |
Ametrine | H | None | Normal | |||
Ammolite | ASBL | Impregnated with colorless hardened substances to increase stability | Commonly | Good to Fair | Special Care | Avoid heat, household chemicals and ultrasonic |
Andalusite | N | None | Normal | |||