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 |
|---|---|---|---|---|---|---|
D | Dyed to provide color and/or uniformity | Commonly | Variable | Special Care | Avoid chemicals and ultrasonic | |
Malachite | W | Coated with colorless wax | Occasionally | Fair | Special Care | Avoid chemicals and ultrasonic |
I | Impregnated with plastic and/or other hardened agents to improve durability and appearance | Rarely | Good | Special Care | Avoid chemicals and ultrasonic | |
Moonstone | O | Oiled to improve clarity | Occasionally | Fair | Normal | Avoid ultrasonic |
Opal | ||||||
White, Black and Semi-Black | O | Impregnated with colorless oil,wax and resins | Rarely | Fair | Special Care | Avoid ultrasonic, heat and solvents |
I | Impregnated with colorless plastic to increase durability and improve appearance | Rarely | Good | Special Care | Avoid heat and solvents | |
Matrix | D | Sugar solution infilling in acid bath to darken background and enhance color play and intensity | Commonly | Good | Special Care | Avoid solvents and repolishing |
Boulder | O | Infusion of unhardened essentially colorless substances into voids to improve appearance | Occasionally | Fair | Special Care | Avoid heat, chemicals, ultrasonic and repolishing |
Fire Opal | N | None | Special Care | Avoid heat | ||
Cat's Eye | I | Impregnated with colorless resins to give durability and improve appearance | Usually | Good | Special Care | Avoid heat, chemicals and ultrasonic |
Hydrophane | O | Impregnated with colorless oil, wax and resins to hide crazing | Commonly | Fair | Special Care | Avoid heat, solvents and ultrasonic |
D | Dyed with colorants | Occasionally | Good | Special Care | Avoid fluids and oils | |
I | Impregnated with colorless plastic to improve appearance and increase durability | Commonly | Good | Special Care | Avoid heat and solvents | |
Pearl | ||||||
Natural | B | Bleached to improve color and appearance | Usually | Very Good | Special Care | Avoid chemicals, cosmetics and ultrasonic |
D | Dyed with or without chemical treatment combined with heat to produce gray to black | Rarely | Very Good | Special Care to Good | Avoid chemicals, cosmetics and ultrasonic |