Gem Enhancement Chart

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Natural Gemstones Enhancements
"Enhancement" - any traditional process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability or availability of a gemstone.

Not Enhanced (N)
The “N” symbol is used on our website to indicate:
gemstones that are not currently known to be enhanced (alexandrite, some garnets, etc.) or
gemstones where it can be proved (via gemological or other means) that a gem has not been subjected to any enhancement.
Normally Enhanced (E)
The “E” symbol indicates that the gemstone has undergone its traditional enhancement process. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, our approach is to assume that such enhancements have been done to that particular gemstone.

Symbols For Specific Forms of Enhancement

B = Bleaching: The use of heat, light and/or chemicals 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 existing color or improve color uniformity.
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 add weight.
H = Heating: The use of heat to alter color, clarity, and/or phenomena.
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, usually diamonds.
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.
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.
U = Diffusion: The use of chemicals in conjunction with high-temperature heat treatment to produce color change and/or asterism-producing inclusions.

W = Waxing/Oiling: The impregnation of a colorless wax, paraffin and/or oil in porous or translucent gemstones to improve appearance.

Natural Gemstones Enhancement Chart
(based on the AGTA Source Directory )

Natural Gemstone	Enhancement Symbol	Description Used	Frequency	Stability	Care Requirements
Agate	D	–	Usually	Excellent to good	Normal
Fire Agate	N	–	–	–	Normal
Alexandrite	N	–	–	–	Normal
Amber	E or H	–	Usually	Very good to good	*Special
	D	–	Rarely	Variable	Special
Amethyst	E or H	–	Occasionally	Excellent	*Special
Ametrine	N	–	–	–	Normal
Andalusite	N	–	–	–	Normal
Aquamarine	E or H	–	Usually	Excellent	Normal
Beryl	R	Maxixe	Always	Poor	X-Special
	R	Yellow	Usually	Variable	Special
	N	Yellow-green	–	–	Normal
	E or O	Red	Commonly	Very good to fair	Special
Chalcedony	D	Black	Always	Excellent to good	Normal
	D	Banded	Usually	Excellent	Normal
	D	Green	Usually	Good to fair	Special
	D	Blue	Commonly	Good to fair	Special
	E or H	Carnelian	Usually	Excellent	Normal
	D	Carnelian	Occasionally	Excellent to good	*Special
	D	Jasper	Occasionally	Excellent	Normal
	N	Chrysoprase	–	–	Normal
Chrysoberyl	N	Transparent	–	–	Normal
	R	Cat’s eye	Occasionally	Excellent	Normal
Citrine	E or H	–	Usually	Excellent	Normal
Coral	N	Black	–	–	*Special
	E or B	White	Commonly	Good	Special
	E or W	Pink	Commonly	Good	Special
	I	Orange	Commonly	Good	Special
	B	Gold	Usually	Very good	Special
	D	Red	Occasionally	Variable	X-Special
Natural Gemstone	Enhancement Symbol	Description Used	Frequency	Stability	Care Requirements
Diamond	L	–	Occasionally	Very good	Normal
	C	–	Rarely	Very good to poor	Special
	F	–	Occasionally	Very good	Special
	HP	–	Rarely	Unknown	Special
Diamond – Fancy	R	–	Occasionally	Excellent to very good	Special
	L	–	Occasionally	Very good	Normal
	F	–	Rarely	Very good	Special
	C	–	Rarely	Fair to poor	Normal
	H	–	Rarely	Unknown	Normal
Diopside – Chrome	N	–	–	–	*Special
Emerald	E or O	–	Usually	Very good to fair	Special
	D	–	Occasionally	Variable	Special
Garnet	N	All varieties	–	–	*Special
	E or H	Some demantoid	Commonly	Very good	*Special
Hematite	N	–	–	–	Normal
Iolite	N	–	–	–	Normal
Jade – Jadeite	E or W	–	Commonly	Fair	Special
	B and I	Green/purple/white	Commonly	Very good to good	Special
	D	–	Occasionally	Variable	Special
	B and W	–	Rarely	Poor	Special
Jade – Nephrite	D	–	Rarely	Unknown	Special
Kunzite	E or H	–	Commonly	Fair	Special
	R	–	Commonly	Fair	Special
Natural Gemstone	Enhancement Symbol	Description Used	Frequency	Stability	Care Requirements
Lapis lazuli	E or W	–	Commonly	Fair	Special
	D	–	Commonly	Variable	Special
Moonstone	N	–	–	–	Normal
Morganite	E or H	–	Commonly	Excellent	Normal
Opal	O	White/black	Rarely	Fair	Special
	I	–	Rarely	Good	Special
	O	Boulder	Usually	Good	Special
	D	Matrix	Commonly	Good	Special
	N	Fire opal	–	–	*Special
	I	Cat’s eye	Usually	Good	Special
	I/O/D	Hydrophane	Commonly	Good to fair	Special
Pearl – Natural	E or B	White	Usually	Very good	Special
	D	–	Rarely	Very good to good	Special
Pearl – Cultured	E or B	White	Usually	Excellent	Special
	D	Many colors	Usually	Variable	Special
	R	Black/gray	Occasionally	Very good	Special
Peridot	E or O	–	Rarely	Good to fair	Special
	F	–	Rarely	Good	Special
Ruby	E or H	–	Usually	Excellent	Normal
	H	–	Usually	Excellent	Normal
	O	–	Occasionally	Good to fair	Special
	D	–	Rarely	Poor	Special
	R	–	Rarely	Unknown	Normal
	F	–	Commonly	Very good to fair	Special
	U	–	Rarely	Good	Special
Natural Gemstone	Enhancement Symbol	Description Used	Frequency	Stability	Care Requirements
Sapphire	E or H	–	Usually	Excellent	Normal
	U	–	Occasionally	Good to fair	Special
	O	–	Occasionally	Good to fair	Special
Sapphire – Fancy	E or H	–	Usually	Excellent	Normal
	R	Yellow/orange	Occasionally	Very poor	X-Special
	O	–	Occasionally	Good to fair	Special
	U	–	Occasionally	Good to fair	Special
Serpentine	D	Various colors	Commonly	Good to fair	Special
	E or W	–	Commonly	Very good to good	Special
Spinel	N	–	–	–	Normal
	O	–	Occasionally	Good to fair	Special
Sugelite	N	–	–	–	Normal
Sunstone	N	–	–	–	Normal
Tanzanite	E or H	–	Usually	Excellent	*Special
Topaz	R	Blue	Usually	Excellent	Normal
	R	Yellow/orange	Occasionally	Variable	Special
	R	Green	Occasionally	Poor	X-Special
	U	Green	Usually	Good	Special
	N	Brown	–	–	*Special
	E or H	Red/pink	Usually	Excellent	Normal
Natural Gemstone	Enhancement Symbol	Description Used	Frequency	Stability	Care Requirements
Tourmaline	N	Chrome green	–	–	Normal
	N	Cat’s Eye	–	–	Normal
	E or H	Yellow/orange	Rarely	Excellent	Normal
	R	Yellow/orange	Rarely	Very good	Normal
	E or H	Green/blue	Commonly	Excellent	Normal
	O	Any color	Occasionally	Good to fair	Special
	E or H	Pink/red/purple	Occasionally	Excellent	Normal
	R	Pink/red/purple	Commonly	Good	Normal
	D	Pink/red/purple	Occasionally	Fair to poor	Special
Turquoise	W	–	Commonly	Fair to poor	Special
	D	–	Rarely	Poor	X-Special
	I	–	Commonly	Good	Special
Zircon	N	Green/brown	–	–	*Special
	E or H	Blue/colorless	Always	Fair to poor	Special
	E or H	Yellow	Rarely	Good	Special
	E or H	Red	Commonly	Fair to poor	Special

Notes:

The “N” symbol is used only for gemstones the seller guarantees have not been enhanced.
All jewelry with or without gemstones requires special care and some need extra special care (X-Special).
* Indicates a gemstone which generally requires special or extra special care although the need for care is not necessarily related to the enhancement.

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GEMFIX
861 6th Ave #608
San Diego, CA 92101
(619) 696-0596

info@gemfix.com