Gemstone Enhancements

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Enhancement of Gemstones

Gemstone enhancement is defined as any treatment process that is used to improve the appearance, durability or availability of a gemstone.
Many gemstones available on the market today are routinely enhanced to impart color, clarity or strength to the stone.

The term "gemstone enhancement" should not be confused with terms such as synthetic, lab-grown, man-made or any other
term which infers the creation of materials.

Natural gemstones are created by natural processes within the earth.
Man-made, lab-grown (or laboratory), or synthetic gems are those created by any non-natural process.

Enhancements of a gemstone can be used on natural or synthetic materials to improve their appearance.
However, a natural gemstone that is enhanced is still considered a Natural gemstone, whereas a synthetic/man-made stone
can never be considered natural whether or not is has received an additional treatment.

The chart below shows the various labels applied to gemstones which denote various enhancement processes.

ENHANCEMENT is defined as any traditional process other than cutting and polishing that improves the
appearance (such as color/clarity/phenomena), durability or availability of a gemstone.

A gemstone enhancement is considered permanent as long as it does not change in appearance
(color and/or clarity) under normal wear, cutting repair, cleaning or display conditions.

Those which are not enhanced
N	The "N" symbol appears on the chart only for natural stones which are not currently known to be enhanced (Alexandrite, Garnet, etc.), however, the "N" symbol can also be used for other natural gemstones in the event that a gemstone has received no enhancement. That gemstone must be accompanied by a commercial document, such as, an invoice, memorandum and/or a laboratory report to support the fact that the gemstone is not enhanced.
Those which are not normally enhanced.
E	The "E" symbol indicates that the gemstone has undergone its traditional enhancement process. The type of enhancement process covered by this symbol is indicated on the following chart. For example: The "E" designation for Aquamarine means only the enhancement that is describes in the chart, i.e. thermal enhancement. In the case of Emerald, the "E" designation refers to the penetration of colorless oil, wax and resins into fissures to improve appearance as the traditional part of the Emerald enhancement process. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, to assume that such traditional enhancement has been done to that particular gemstone.
SYMBOLS FOR SPECIFIC FORMS OF ENHANCEMENTS:
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, which are visible under properly illuminated 10X magnification. This process will improve durability, appearance and/or add weight.
H	Heating: The use of heat to affect desired alteration of color, and/or phenomena. (Residue of foreign substances in open fissures is not visible under properly illuminated 10X magnification.)
HP	Heating and Pressure: The use of heat and pressure combines 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.
L	Lasering: The use of laser and chemicals to reach and alter inclusions in 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 requiring an environmental safety release from the Nuclear Regulatory Commission (NRC), Gamma 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 temperatures to produce color and/or asterism producing inclusions.
W	Waxing/Oiling: The impregnation of a colorless wax, paraffin and oil in porous opaque or translucent gemstones to improve appearance.
SYNTHETIC STONES
SYN	The tag code may be used to describe "synthetic" materials that have essentially the same optical, physical and chemical properties as a naturally occurring counterpart. The code name may not be used as a noun; thus a stone must not be referred to as a "synthetic." In all cases, the name of the stone must also be used; thus, a stone must be referred to as "synthetic emerald," synthetic ruby," etc. Synthetic stones are as stable in color and composition as their natural counterpart.
IMITATION PRODUCTS-SIMULANTS (SUBSTITUTES)
IMIT	"IMIT" is the tag code used for a manufactured product fabricated in such materials as glass, ceramic or plastic designated to imitate or resemble the appearance, but not duplicate the characteristic properties of a natural gemstone. These materials require special care; avoid household chemicals, cosmetics, abrasives and sudden shocks. "IMIT" is also the tag code for a simulant, which is defined as a man-made single crystal product that is used to simulate the appearance, but not duplicate the properties of the natural gemstone it imitates. Example are: synthetic Spinel; synthetic Sapphire, synthetic Quartz and synthetic Cubic Zirconia produced in various colors to imitate gemstones of different species. This designation also includes GGG, strontium titanate and YAG. This category also includes non-single crystal materials such as imitation Lapis Lazuli and imitation Coral.
ASSEMBLED MATERIALS (COMPOSITE)
ASBL	"ASBL" is the tag code for products made of multiple layers or combinations of manufactured and/or natural materials fused, bonded or otherwise joined together to increase stability and/or to imitate the appearance of a natural gemstone, create a unique design or generate color combinations. Examples:
ASBL	Opals-(various Combinations) Doublets and Triplets
ASBL	Garnet-Glass Doublets
ASBL	Sapphire-Synthetic Sapphire Doublets
ASBL	Colorless Beryl-joined by green bonding (Triplets)
ASBL	Mabe "Pearls" color coated, dyed, bleached, filled with hardened substances and a Mother of Pearl back. Sometimes coating can be plastic or polymer to protect the thin nacre.
ASBL	Bonded material such as Turquoise, Lapis, etc. The "ASBL" coded stones require extra special care; avoid household chemicals, cosmetics, abrasives and sudden shocks.

Various Gemstones and their possible enhancements

GEMSTONE	TAG CODE	ENHANCEMENT METHOD	FREQUENCY USED	STABILITY	CARE REQUIRED	SPECIAL ADVICE
Alexandrite	N	None	-----	----	Normal
Amazonite	E or W I	Impregnated with a colorless wax, paraffin or oil to improve appearance Impregnated with plastic and other hardness resins to improve appearance	Usually Usually	Good to fair Very good	Special Special	Avoid heat, chemical and ultrasonic Avoid chemicals and ultrasonic
Amber	E or H D	Heated to improve appearance, add "sun spangles" or deepen color Dyed of surface treated to add color	Usually Rarely	Very good to Good Variable	Special Special	Avoid chemicals and ultrasonic Avoid repolishing surface, chemicals and ultrasonic
Amethyst	E or H	Heated to lighten color and/or to remove "Smokey" components	Occasionally	Excellent	Special	Some unheated material may fade in long exposure to sunlight
Ametrine	N	None	----	----	Normal
Ammolite	I	Impregnated with colorless hardened substances to increase stability	Usually	Good to fair	Special	Avoid heat, household chemicals and ultrasonic
Andalusite	N	None	----	----	Normal
Aquamarine	E or H	Heated to remove yellow components thereby producing a purer blue color	Usually	Excellent	Normal
Beryl Blue Pink Yellow-Green Red Yellow	R E or H N E or O R	Irradiated blue from pale pink or colorless Heated to remove yellow component thereby producing a pure pink color None The penetration of colorless oil and resins into fissures to improve appearance Produced by irradiation	Always Commonly ----------- Commonly Usually	Poor Excellent ---------- Very good to fair Variable	Extra Special Normal Normal Special Normal / Special depending on method	Color fades, avoid light and heat Avoid high temperatures steam cleaning, chemicals and ultrasonic Certain stones may fade in light or heat depending on method
Chalcedony Agate Black (Onyx) Banded Blue Green Carnelian Jasper Chrysoprase	D D D D D E or H D D N	Dyed Dyed Dyed Dyed Dyed Heated to produce color Dyed to produce color Sometimes dyed to imitate other stones None	Usually Always Usually Commonly Usually Usually Occasionally Occasionally ----	Excellent to Good Excellent to Good Excellent Good to fair Good to fair Excellent Excellent to Good Excellent -----	Normal Normal Normal Special Special Normal Special Normal Normal	Certain stones may fade in light or heat Certain stones may fade in light or heat Certain stones may fade in light or heat
Chrysoberyl Cat's Eye Transparent Varieties: Yellow Brown Green	R N N N	Irradiated to change color None None None	Occasionally ----- ----- -----	Excellent ----- ----- -----	Normal Normal Normal Normal	For safety requirements, if neutron irradiated, refer to code letter "R" in gemstone information
Citrine	E or H	Produced by heating various types of quartz	Usually	Excellent	Normal
Coral Black White Pink Orange "Gold" Red	N E or B E or W I B D	None Bleached Impregnated with colorless wax Stabilized with plastic to improve color and durability Bleached from black coral Dyed	----- Commonly Commonly Commonly Usually Occasionally	----- Good Good Good Very Good Variable	Special Special Special Special Special Special to extra special depending on type of dye	Avoid chemicals, cosmetics and ultrasonic Avoid chemicals, cosmetics and ultrasonic: material may discolor in time Avoid chemicals and ultrasonic Same as above Avoid chemicals and ultrasonic Certain materials may fade in light or heat. Avoid chemicals, cosmetics and ultrasonic
Diamond Colorless to faint Yellow Colored	L C F HP L F R C H	Laser drilled to improve appearance Coated to disguise off-color Filling of surface cavities or fractures with a hardened substance Use of heat with pressure to alter color and/or clarity Laser drilled to improve appearance Filling of surface cavities or fractures with a hardened substance Irradiated and/or heated to induce "fancy" colors Coated to "fancy" colors Use of heat to alter color	Occasionally to common Rarely Occasionally Rarely Occasionally Rarely Occasionally Rarely Rarely	Very Good Very good to poor depending on method Very Good Unknown Very good Very good Excellent to very good Fair to poor Unknown	Normal Variable Special Normal Normal Special Normal except green Special Normal	Recutting, steam cleaning, ultrasonic and occasionally alcohol may adversely affect color and appearance Recutting or extreme heat may remove filling material Recutting or extreme heat may remove filling material Avoid heating treated green stones as the color may change. Some green stones have been radium irradiated. For safety requirements refer to the NRC. Recutting, steaming and ultrasonic may adversely affect color and appearance
Diopside (Chrome)	N	None	----	----	Special	Avoid sudden temperature changes and harsh chemicals
Emerald	E or O D	The penetration of colorless oil, wax and resins into fissures to improve appearance Dyed with colored agents	Usually Occasionally	Very good to fair Variable	Special Special	Avoid sudden temperature changes, steaming, chemicals and ultrasonic Same as above
Garnet Almandite Demantoid Grossularite Pyrope Rhodolite Spessarite Tsavorite	N N N N N N N	None None None None None None None	---- ---- ---- ---- ---- ---- ----	---- ---- ---- ---- ---- ---- ----	Normal Normal Normal Normal Normal Normal Normal	Avoid sudden temperature change Same as above Same as above Same as above Same as above Same as above Same as above
Hematite	N	None	----	----	Normal
Iolite	N	None	----	----	Normal
Ivory & Bone Mammoth (Ivory)	E or B D W I	Bleached to whiten and remove discoloration Dyed for artistic purposes Impregnated with colorless paraffin wax Impregnated with colorless hardened substances to increase stability	Commonly Occasionally Occasionally Commonly	Good Good Good Good	Special Special Special Normal	Avoid chemicals and ultrasonic: may discolor in time Same as above Same as above
Jade Jadeite Green, White and Purple Nephrite	E or W B and W B and S D D	Coated with colorless wax Two-step bleaching and wax impregnation Two-step bleaching and polymer impregnation Dyed to imitate natural colors Dyed selectively to alter color for artistic purposes in carvings	Commonly Rarely Commonly Occasionally Rarely	Fair Poor Very good to good Variable Unknown	Normal to Special Special Special Special Special	Avoid ultrasonic Avoid heat, chemicals and ultrasonic same as above Avoid strong light, chemicals and ultrasonic: may discolor in time. Avoid chemicals, ultrasonic and strong light
Kunzite	E or H R	Heated to improve color from certain locations Irradiated and heated to darken color	Commonly Commonly	Fair Fair	Special Special	Natural and/or treated materials may fade-avoid strong light, ultrasonic Same as above
Lapis Lazuli	E or W D	Coated with colorless wax or oil to improve appearance Dyed to provide color and/or uniformity	Commonly Commonly	Fair Variable	Normal to special Special	Avoid chemicals and ultrasonic Same as above
Malachite	W I	Coated with colorless wax Impregnated with plastic and/or other hardened agents to improve durability and appearance	Occasionally Rarely	Fair Good	Special Special	Avoid chemicals and ultrasonic Same as above
Moonstone	N	None	----	----	Normal
Opal White, Black & Semi-Black Matrix Boulder Fire Opal Cat's Eye Hydrophane	O I D O N I O D I	Impregnated with colorless oil, wax and resins Impregnated with colorless plastic to increase durability & improve appearance Sugar solution infilling in acid bath to darken background and enhance color play and intensity Infusion of unhardened essentially colorless substances into voids to improve appearance None Impregnated with colorless resins to give durability and improve appearance Impregnated with colorless oil, wax and resins to hide crazing Impregnated with hardened agents to improve appearance and increase durability Impregnated with colorless plastic to improve appearance and increase durability	Rarely Rarely Commonly Occasionally ---- Usually Commonly Commonly Commonly	Fair Good Good Fair ---- Good Fair Good Good	Special Special Special Special Special Special Special Special Special	Avoid ultrasonic, heat and solvents Avoid heat and solvents Avoid solvents and repolishing Avoid heat, chemicals, ultrasonic and repolishing Avoid heat Avoid heat, solvents and ultrasonic Avoid heat, solvents and ultrasonic Avoid heat and solvents Avoid heat and solvents
Pearl Natural Cultured Mabe 'Pearl'	E or B D E or B D D D R D	Bleached to improve color and appearance Dyed with or without chemical treatment combined with heat to produce gray to black. Bleached to improve color and uniformity of white color only Dyed to give rose, blue or golden overtones Dyed blue, black and other colors includes use of colored nuclei Dyed all colors (freshwater) Irradiated to produce blue, gray black and bronze colors Chemical treatment combined with heat to produce gray to black See assembled materials	Usually Rarely Usually Usually Occasionally Usually Occasionally Commonly	Very good Very good to good Excellent Good Variable Very good Very good Very good to good	Special Special Special Special Special Special Special Special Extra Special	Avoid cosmetics and household chemicals Avoid chemicals, cosmetics and ultrasonic Same as above Same as above Same as above Same as above Same as above Same as above Avoid household chemicals, cosmetics, abrasives and sudden shocks
Peridot	E or O F	Penetration of colorless oil, wax and resins into voids to improve appearance Filling of surface fractures with a colorless hardened substance	Rarely Rarely	Good to fair Good	Special Special	Avoid sudden temperature changes, harsh chemicals and ultrasonic Same as above
Rhodonite	D	Dyed to "even out color"	Occasionally	Poor	Special	Avoid chemicals and ultrasonic
Ruby	E or H D F R U	Heated to improve color and appearance (Residue of foreign substance is not visible under 10X magnification.) Dyed with colored oil to improve appearance Intentional filling of surface cavities and fractures with a foreign material, including glass which is visible under 10X magnification Irradiated to change color Diffusion of color or asterism in corundum at or near the surface	Usually Rarely Commonly Rarely Rarely	Excellent Poor Very good to fair Unknown Good	Normal Special Special Normal Special	Avoid household chemicals and ultrasonic Fracture filling in Rubies may be fragile and may fall out under extreme pressure; avoid heat and ultrasonic For safety requirements, if neutron irradiated, refer to code letter "R" Avoid repolishing or recutting
Sapphire	E or H U R	Heated to produce, intensity or lighten color and/or improve color uniformity and appearance Diffusion of color or asterism at or near the surface, usually blue Irradiation to provide temporary intense yellow or orange color	Usually Occasionally Occasionally	Excellent Good Very Poor	Normal Special Extra Special	Avoid repolishing or recutting Fades quickly in light or heat
Serpentine	D E or W	Dyed various colors Impregnated with colorless wax	Commonly Commonly	Good to fair Very good to good	Special Special	Dye may fade Avoid ultrasonic
Sodalite	D	Dyed	Rarely	Fair	Special	Dye may fade
Spinel	N	None	----	----	Normal
Spodumene Green Yellow	R R	Irradiated to produce green color Irradiated to produce yellow color	Rarely Rarely	Poor Poor	Extra special Extra special	Color fades in light or heat Same as above
Sugilite	N	None	----	----	Normal
Tanzanite	E or H	Heated to produce violet-blue color	Usually	Excellent	Special	Avoid sudden temperature changes
Topaz Blue Yellow/Orange Pink/Red Brown Green Green	R R E or H N R U	Irradiated brown and often heated to produce blue color Irradiated to intensify color Heated chromium-bearing pinkish-brown to orange stones Normal Irradiated to produce a green color Diffusion of color at or near the surface	Usually Occasionally Usually ---- Occasionally Usually	Excellent Variable Excellent ---- Poor Good	Normal Special Normal Special Extra special Special	For safety requirements, if neutron irradiated, refer to code letter "R" Avoid heat and strong light May fade in exposure to sunlight Color fades in exposure to sunlight Avoid repolishing or recutting
Tourmaline Chrome Vanadium Cat's Eye Yellow/Orange Green, Blue Pink, Red, Purple	N N E or H R E or H O E or H R O D	None None Heated to improve color Irradiated to improve color Heated to improve color The penetration of colorless oil or resins into voids to improve appearance Heated to improve color Irradiated to intensify color Penetration of colorless oil or unhardened resins into voids to improve appearance Penetration of coloring agents into voids to improve appearance	---- ---- Rarely Rarely Commonly Occasionally Occasionally Commonly Occasionally Occasionally	---- ---- Excellent Very Good Excellent Good to fair Excellent Good Good to fair Fair to poor	Normal Normal Normal Normal Normal Special Normal Normal Special Special	Avoid temperature changes, steaming, chemicals and ultrasonic Same as above Same as above
Turquoise	I W D	Impregnated with plastic to create or improve color and increase durability Impregnated with colorless oil or wax to enhance or create color Dyed to improve color	Commonly Commonly Rarely	Good Fair to poor Poor	Special Special Extra special	Avoid hot water and household chemicals Same as above Same as above
Zircon Green, Brown Yellow Blue and colorless Red	N E or H E or H E or H	None Heated to improve color Brownish crystals are heated to these colors Heated to change brownish crystal to red	---- Rarely Always Commonly	---- Good Fair to poor Fair to poor	Special Special Special Special	Avoid harsh abrasives Same as above Same as above Same as above

GEMSTONE PROPERTIES AND ENHANCEMENTS
MATERIAL	SPECIFIC GRAVITY		HARDNESS	REFRACTIVE INDEX			ENHANCEMENT		SPECIAL CARE
MATERIAL	SPECIFIC GRAVITY		HARDNESS	Normal	Range	Bire.	Most Commonly Used Method	Code	SPECIAL CARE
Alexandrite	3.73	±.02	8 ½	1.746 – 1.755	+.004 –.006	.008– .010	None	A	Normal
Amethyst	2.66	+.03 –.02	7	1.544 – 1.553	±.000	.009	None	A	Normal
Andalusite	3.17	± .04	7 - 7 ½	1.634 - 1.643	±.005	.007– .013	None	A	Normal
Aquamarine	2.72	+.18 –.05	7 ½ - 8	1.577 - 1.583	±.017	.005– .009	Heated	H	Normal
Ametrine	2.66	+.03 –.02	7	1.544 - 1.553	±.000	.009	None	A	Normal
Beryl	2.72	+.18 –.05	7 ½ - 8	1.577 - 1.583	±.017	.005– .009	None	A	Normal
Chrysoberyl	3.73	±.02	8 ½	1.746 - 1.755	+.004 –.006	.008– .010	None	A	Normal
Citrine	2.66	+.03 –.02	7	1.544 - 1.553	±.000	.009	Heated	H	Normal
Diamond	3.52	±.01	10	2.417	---	---	None	A	Normal
Emerald	2.72	+.18 –.05	7 ½ - 8	1.577 - 1.583	±.017	.005– .009	Oiled	O	Avoid temp. changes, steaming, chemicals and ultrasonic.
Garnet	3.78	+.09 –.16	7 - 7 ½	1.746	+.010 –.026	---	None	A	Avoid sudden temperature changes.
Iolite	2.61	±.05	7 - 7 ½	1.542 - 1.551	+.045 –.011	.008– .012	None	A	Normal
Kunzite	3.18	±.03	6 ½ - 7	1.660 - 1.676	±.005	.014– .016	Irradiated	R	Avoid strong light and ultrasonic - color may fade
Opal	2.15	+.08 –.90	5 - 6 ½	1.450	+.020 –.080	---	None	A	Avoid heat, chemicals and ultrasonic.
Peridot	3.34	+.14 –.07	6 ½ - 7	1.654 - 1.690	±.020	.035– .038	None	A	Avoid sudden temperature changes and chemicals.
Rhodolite	3.84	±.10	7 - 7 ½	1.760	+.010 –.020	---	None	A	Avoid sudden temperature changes.
Rubellite	3.06	+.20 –.06	7 - 7 ½	1.624 - 1.644	+.011 –.009	.018– .040	Irradiated	R	Normal
Ruby	4.00	+.10 –.05	9	1.762 - 1.770	+.009 –.005	.008– .010	Heated	H	Normal
Sapphire	4.00	+.10 –.05	9	1.762 - 1.770	+.009 –.005	.008– .010	Heated	H	Normal
Spinel	3.60	+.10 –.03	8	1.718	±.017	---	None	A	Normal
Tanzanite	3.35	+.10 –.25	6 - 7	1.691 - 1.700	±.005	.008– .013	Heated	H	Avoid sudden temperature changes and ultrasonic.
Tsavorite	3.61	+.12 –.04	7 - 7 ½	1.740	+.020 –.010	---	None	A	Avoid sudden temperature changes.
Topaz	3.53	±.04	8	1.619 - 1.627	±.010	.008– .010	Irradiated & Heated	R	Normal
Tourmaline	3.06	+.20 –.06	7 - 7 ½	1.624 - 1.644	+.011 –.009	.018– .040	Heated	H	Normal
Zircon	4.70	+.03 –.80	6 - 7 ½	1.925 - 1.984	+.040 –.145	.000– .059	Heated	H	Avoid Abrasives