AGTA Treatment Codes

Introduction

Many Gemstones are treated and have been from the onset of the gemstone industry.

Over time new treatments have and continue to been introduced.

Stonemangems will always disclose any industry accepted treatments within the specifications of a particular gemstone in adherence to AGTA guidelines.

Stonemangems * Allan A. Goldman Inc. has been a member of the AGTA, (American Gemstone Association),since its inception in 1981.

The Symbols and AGTA enhancement chart that is for purposes of helping you understand the various treatment types that are commonly applied to gemstones in addition the care that should be applied.

Definition of Enhancement

Enhancement: Any traditional process other than cutting and polishing that improves the appearance, (color/clarity/phenomena), durability or availability of a gemstone.

A gemstone enhancement is considered permanent as long as the effect of the enhancement does not change under normal wear, cutting, repair, cleaning or display conditions.

If a gemstone enhancement is not permanent, appropriate disclosure is required.

Please keep in mind that many of the materials shown in the chart that display traditional treatments, especially those that are noted as "Rarely" enhanced are often not enhanced at all and completely "N" Natural.

In those cases the item will be AGTA rated "N".

Defined below are the specific enhancement codes and designations that are used in the AGTA gemstone enhancement information chart.

AGTA SYMBOLS FOR SPECIFIC FORMS OF ENHANCEMENT
N Natural: No modification (or currently has no known modification process).
ASBL Assembled: Material made up more than one material.Some or all components can be natural but still boned together.
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 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 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. This process may improve durability and/or appearance, and/or to add weight.
H Heating: The use of heat to effect desired alteration of color, clarity and/or phenomena. If residue of foreign substances in open fissures is visible under properly illuminated 10X magnification, H F should be used.
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 in gemstones, usually 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, gamma rays or beta particles (high energy electrons) to alter a gemstone's color. The irradiation may be followed by a heating process.
SIM Simulated: Man-made material with only the visual qualities as their genuine counter-part.
SYN Synthetic: Man-made material with the same physical, chemical and visual qualities as their genuine counter-part.
U Diffusion: The use of chemicals in conjunction with high temperatures to produce ARTIFICIAL color change and/or asterism-producing inclusions.
W Waxing/Oiling: The impregnation of a colorless wax, paraffin or oil in porous opaque or translucent gemstones to improve appearance.
Gemstone AGTA Information Chart Glossary
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
Apatite H Heated to improve color Commonly Good Normal
R Irradiated to improve color Occasionally Fair to Poor Special Care Avoid heat
Aquamarine H Heated to remove yellow component, thereby producing a pure blue color Usually Excellent Normal
Beryl
Blue ("Maxixe" Type) R Irradiated blue from pale pink to colorless Always Poor Extra Special Color fades, avoid light and heat
Pink R Irradiated to improve color Rarely Fair care Avoid heat
Yellow-Green N None Normal
Red O The penetration of colorless oil and resins into fissures to improve appearance Commonly Very Good to Fair Special Care Avoid high temperatures, steam cleaning, chemicals and ultrasonic
Yellow R Produced by irradiation Usually Variable Normal/Special Care depending on method Certain stones may fade in light or heat
Chalcedony
Agate D Dyed Usually Excellent to Good Normal
Black (Onyx) D Dyed Always Excellent to Good Normal
Banded D Dyed Usually Excellent Normal
Blue D Dyed Commonly Good to Fair Special Care Certain stones may fade in light or heat
Green D Dyed Usually Good to Fair Special Care Certain stones may fade in light or heat
Carnelian H Heated to produce color Usually Excellent Normal
D Dyed to produce color Occasionally Excellent to Good Special Care Certain stones may fade in light or heat
Jasper W Waxed Commonly Fair Normal Avoid chemicals
Chrysoprase N None Normal
Chrysoberyl
Cat's Eye R Irradiated to change color Rarely Excellent Normal
Transparent Varieties:
Yellow N None Normal
Brown N None Normal
Green N None Normal
Citrine H Produced by heating various types of quartz Usually Excellent Normal
Diamond
Colorless to Faint Yellow L Laser drilled to improve appearance Occasionally to Commonly Very Good Normal
C Coated to disguise off-color Rarely Very Good to Poor Depending on Method Variable Recutting, steam cleaning, ultrasonic and occasionally alcohol may adversely affect color and appearance
F Surface cavities or fractures filled with a hardened substance Occasionally Very Good Special Care Recutting or extreme heat may remove filling material
HP Heated with pressure to alter color and/or clarity Rarely Unknown Normal
Colored L Laser drilled to improve appearance Occasionally Very Good Normal
F Surface cavities or fractures filled with a hardened substance Rarely Very Good Special Care Recutting or extreme heat may remove filling material
R Irradiated and/or heated to induce Occasionally Excellent to Normal Avoid heating treated green stones as the color
"fancy" colors Very Good except green may change. Some green stones have been radium irradiated for safety requirements: refer to the NRC
C Coated to "fancy" colors Rarely Fair to Poor Special Care Recutting, steaming and ultrasonic may adversely affect color and appearance
H Heated to alter color Rarely Unknown Normal
HP To create fancy colors Commonly Excellent
Diopside (Chrome) N None Special Care Avoid sudden temperature changes and harsh chemicals
Emerald O The penetration of colorless oil. wax and resins into fissures to improve appearance Usually Very Good to Fair Special Care Avoid sudden temperature changes, steaming, chemicals and ultrasonic
D Dyed with color agents Occasionally Variable Special Care Avoid sudden temperature changes, steaming, chemicals and ultrasonic
Garnet
Almandite N None Normal Avoid sudden temperature change
Demantoid H To improve color Occasionally Good Normal Avoid sudden temperature change
Grossularite N None Normal Avoid sudden temperature change
Pyrope N None Normal Avoid sudden temperature change
Rhodolite N None Normal Avoid sudden temperature change
Spessartite N None Normal Avoid sudden temperature change
Tsavorite N None Normal Avoid sudden temperature change
Hematite N None Normal
lolite N None Normal
Ivory and Bone B Bleached to whiten and remove discoloration Commonly Good Special Care Avoid chemicals and ultrasonic, may discolor in time
D Dyed for artistic purposes Occasionally Good Special Care Avoid chemicals and ultrasonic, may discolor in time
W Impregnated with colorless paraffin wax Occasionally Good Special Care Avoid chemicals and ultrasonic, may discolor in time
Jade
Jadeite W Coated with colorless wax Commonly Fair Normal to Special Care Avoid ultrasonic
B or W Two-step bleaching and wax impregnation Rarely Poor Special Care Avoid heat, chemicals and ultrasonic
Green, White Band and Purple B and S Two-step bleaching and polymer impregnation Commonly Very Good to Good Special Care Avoid heat, chemicals and ultrasonic
D Dyed to imitate natural colors Occasionally Variable Special Care Avoid strong light, chemicals and ultrasonic, may discolor in time
Nephrite D Dyed selectively to alter color for artistic purposes in carvings Rarely Unknown Special Care Avoid chemicals, ultrasonic and strong light
Kunzite H Heated to improve color from certain locations Commonly Fair Special Care Natural and/or treated materials may fade - avoid ultrasonic and strong light
R Irradiated and heated to darken color Commonly Fair to Poor Special Care Natural and/or treated materials may fade - avoid heat, ultrasonic and strong light
Kyanite O The penetration of colorless oil into fissures to improve appearance Occasionally Fair Special Care Avoid sudden temperature changes, steaming, chemicals and ultrasonic
Lapis Lazuli W Coated with colorless wax or oil to improve appearance Commonly Fair Normal to Special Care Avoid chemicals and ultrasonic
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
Cultured B Bleached to improve color and uniformity of white color only Usually Excellent Special Care Avoid chemicals, cosmetics and ultrasonic
D Dyed to give rose, blue or golden overtones Usually Good Special Care Avoid chemicals, cosmetics and ultrasonic
D Dyed blue, black and other colors includes use of colored nuclei Occasionally Variable Special Care Avoid chemicals, cosmetics and ultrasonic
D Dyed all colors (freshwater) Usually Very Good Special Care Avoid chemicals, cosmetics and ultrasonic
R Irradiated to produce blue, gray, black and bronze colors Occasionally Very Good Special Care Avoid chemicals, cosmetics and ultrasonic
D Chemical treatment combined with heat to produce gray to black.
Commonly Very Good to Good Special Care Avoid chemicals, cosmetics and ultrasonic
Mabe "Pearl" ASBL Assembled Extra Special Care Avoid household chemicals, cosmetics, abrasives and sudden shock
Peridot O Penetration of colorless oil, wax and resins into voids to improve appearance Rarely Good to Fair Special Care Avoid sudden temperature changes, harsh chemicals and ultrasonic
F Surface fractures filled with a colorless hardened substance Rarely Good Special Care Avoid sudden temperature changes, harsh chemicals and ultrasonic
Rhodonite D Dyed to "even out color" Occasionally Poor Special Care Avoid chemicals and ultrasonic
Ruby H Heated to improve color and appearance (residue of foreign substance is not visible under 10X magnification) Usually Excellent Normal
D Dyed with colored oil to improve appearance Rarely Poor Special Care Avoid household chemicals and ultrasonic
F Intentional filling of surface cavities and fractures with a foreign material, including glass, which is visible under 10X magnification Commonly Fair to Poor Special Care Fracture filling requires special care.Avoid heat, ultrasonic and common household chemicals.
R Irradiated to change color Rarely Unknown Normal
U Diffusion with an element or elements (with the exception of hydrogen) into the lattice of a stone during the application of heat to create artificial color or asterism. Occasionally Excellent or good when effect is not near surface Normal
U Effects may be throughout the stone or at or near the surface. Occasionally Normal or Special when effect is near surface Special Care Avoid repolishing or recutting when effect is near surface
Sapphire H Heated to produce, intensify or lighten color and/or improve color uniformity and appearance Usually Excellent Normal
U Diffusion with an element or elements (with the exception of hydrogen) into the lattice of a stone during the application of heat to create artificial color or asterism. Commonly Good when effect is not near surface Normal
Effects may be throughout the stone or at or near the surface. Most colors may be produced. Normal or Special when effect is near surface Special Care Avoid repolishing or recutting when effect is near surface.
R Irradiated to provide temporary intense yellow or orange color Occasionally Very Poor Extra SpeciaL Care Fades quickly in light or heat
Serpentine D Dyed various colors Commonly Good to Fair Special Care Dye may fade
W Impregnated with colorless wax Commonly Very Good to Good Special Care
Sodalite D Dyed Rarely Fair Special Care Dye may fade
Spinel N None Normal
Spodumene
Green or Yellow R Irradiated to produce green color Rarely Poor Extra Special Care Color fades in light or heat
Sugilite D Improvement of color Fair Normal Avoid chemicals
Tanzanite H Heated to produce violet-blue color Usually Excellent Special Care Avoid sudden temperature changes and harsh abrasives
Topaz
Blue R Irradiated brown and often heated to produce blue color Usually Excellent Normal
Yellow/Orange R Irradiated to intensify color Occasionally Variable Special Care Avoid heat and strong light
Pink/Red H Heated chromium-bearing pinkish-brown to orange stones Usually Excellent Normal
Brown N None Special Care May fade in exposure to sunlight
Green R Irradiated to produce a green color Occasionally Poor Extra Special Color fades in exposure to sunlight
Green U Diffusion of color at or near surface. See Specific Forms of Enhancement, page 7 Usually Good Special Care Avoid repolishing or recutting
All Colors C Any substance applied to the surface of the gemstone to artificially modify color and/or appearance Commonly Poor Special Care Avoid repolishing or recutting, steaming, chemicals or ultrasonic
Tourmaline
Chrome Vanadium N None Normal
Cat's Eye N None Normal
Yellow/Orange H Heated to improve color Rarely Excellent Normal
R Irradiated to improve color Rarely Very Good Normal
Green, Blue H Heated to improve color Occasionally Excellent Normal
O The penetration of colorless oil or resins into voids to improve appearance Occasionally Good to Fair Special Care Avoid temperature changes, steaming chemicals and ultrasonic.
Pink, Red, Purple H Heated to improve color Occasionally Excellent Normal
R Irradiated to intensify color Commonly Good Normal
O Penetration of colorless oil or unhardened resins into voids to improve appearance Occasionally Good to Fair Special Care Avoid temperature changes steaming chemicals and ultrasonic.
D Penetration of coloring agents into voids to improve appearance Occasionally Fair to Poor Special Care Avoid temperature changes. steaming chemicals and ultrasonic.
Turquoise I Impregnated with plastic to create or improve color and increase durability Commonly Good Special Care Avoid hot water and household chemicals
W Impregnated with colorless oil or wax to enhance or create color Commonly Fair to Poor Special Care Avoid hot water and household chemicals
Z Zachery Treatment. Electrocution sealing the pours of the material Commonly Excellent Normal
D Dyed to improve color Rarely Poor Extra Special care Avoid hot water and household chemicals
Zircon
Green, Brown N None Good Special Care Avoid harsh abrasives
Yellow H Heated to improve color Rarely Good Special Care Avoid harsh abrasives
Blue and Colorless H Brownish crystals are heated to these colors Always Good Special Care Avoid strong UV light
Red H Heated to change brownish crystals to red Commonly Good Special Care Avoid harsh abrasives and strong UV light
Pink H Improves color to pink Usually Good Special Care Avoid harsh abrasives and strong UV light