Gemstone Enhancements and Treatments

The fashioning of gemstones is a skillful blend of art and science. Art is used to shape, facet and polish. Science is used to attain the finest color and appearance. As part of its commitment to consumer education, Certified Jewelry Appraisals presents this comprehensive directory of gems, including well known as well as rare and exotic varieties. It also covers enhancement methods known or believed to help these gems reach their full potential for beauty or improve their durability.

Gemstone	Hard	Method	Cd	Frequ	Stab	Care/Handling
Abalone
Shell	3-4	none	N	n/a	n/a	avoid heat / harsh chemicals / perfumes / hairsprays
Pearl	2.5-4	none	N	n/a	n/a	avoid heat / harsh chemicals / perfumes / hairsprays
Agate - see Chalcedony
^ Top
Alexandrite	8.5	none	N	n/a	n/a	normal care
Almandite - see Garnet
Amazonite - see Feldspar
^ Top
Amber
Amber	2-2.5	none	N	r	n/a	very soft / avoid harsh chemicals and ultrasonic
Amber	2-2.5	heated to improve appearance or deepen color	E/H	u	g-vg	very soft / avoid harsh chemicals and ultrasonic
Amber	2-2.5	dyed or surface treated to add color	D	r	v	avoid repolishing, harsh chemicals and ultrasonic
^ Top
Amblygonite	6	none	N	n/a	n/a	*Research in Progress
Amethyst - see Quartz
Ametrine - see Quartz
^ Top
Ammonite / Ammolite	4	impregnated with colorless hardened substances to increase stability	I	u	f-g	avoid heat, harsh chemicals and ultrasonic
^ Top
Andalusite	7-7.5	none	N	n/a	n/a	normal care
Andradite - see Garnet
^ Top
Apatite
Apatite	5	none	N	r	n/a	moderately soft, avoid heat, harsh chemicals and ultrasonic
Apatite	5	heated to improve appearance or deepen color	H	u	g	moderately soft, avoid heat, harsh chemicals and ultrasonic
Aquamarine - see Beryl
^ Top
Aragonite	3.5-4	none	N	n/a	n/a	soft/avoid heat, harsh chemicals and ultrasonic; generally unsuitable for jewelry
Aventurine - see Quartz
^ Top
Azurite	3.5-4	coated with colorless wax	C	o	f-g	soft/avoid heat, harsh chemicals and ultrasonic
^ Top
Azurmalachite	3.5-4	filled with epoxy or resin	I	r	f-g	soft/avoid heat, harsh chemicals and ultrasonic
^ Top
Benitoite	6.5	none	N	n/a	n/a	avoid heat, harsh chemicals and ultrasonic
^ Top
Beryl
Aquamarine	7.5-8	none	N	vr	n/a	normal care
Aquamarine	7.5-8	heated to improve color	E/H	u	et	normal care
Blue (Maxixe)	7.5-8	irradiated blue from pale pink or colorless	R	a	p	extra special - avoid light and heat/color fades
Colorless (Goshenite)	7.5-8	none	N	n/a	n/a	normal care
Emerald	7.5-8	none	N	er	n/a	avoid sudden temperature change, ultrasonic and chemicals
Emerald	7.5-8	dyed with colored agents	D	o	v	avoid sudden temperature changes, chemicals and ultrasonic
Emerald	7.5-8	penetration of colorless oils, wax and resins into fissures to improve appearance	E/O	u	f-vg	avoid sudden temperature changes, chemicals and ultrasonic
Pink (Morganite)	7.5-8	heated to remove yellow	E/H	c	e	normal care
Red (Bixbite)	7.5-8	none	N	r	n/a	avoid high temperatures, steam cleaning, chemicals, ultrasonic
Red (Bixbite)	7.5-8	colorless oil and resins to improve appearance	E/O	c	f-vg	avoid high temperatures, steam cleaning, chemicals, ultrasonic
Yellow	7.5-8	irradiated to produce color	R	u	v	normal care, but some stones may fade in light or heat
Green - Yellow	7.5-8	none	N	n/a	n/a	normal care
Carnelian - see Chalcedony
Cat's eye - see Chrysoberyl
Bone - see Ivory
^ Top
Chalcedony
Agate	6.5-7	dyed	D	u	g-e	normal care
Black Onyx	6.5-7	dyed	D	a	g-e	normal care
Banded Agate	6.5-7	dyed	D	u	e	normal care
Bloodstone	6.5-7	*Research in Progress	*	*	*	normal care - *Research in Progress
Blue Chalcedony	6.5-7	dyed	D	c	f-g	may fade in light or heat
Carnelian	6.5-7	heated to produce color	E/H	u	e	normal
Carnelian	6.5-7	dyed to produce color	D	o	g-e	certain stones may fade in light or heat
Chrysoprase	6.5-7	none	N	n/a	n/a	normal care
Dendritic Agate	6.5-7	none	N	n/a	n/a	normal care
Fire Agate	6.5-7	none	N	n/a	n/a	normal care
Green Chalcedony	6.5-7	dyed to produce color	D	u	f-g	may fade in light or heat
Moss Agate	6.5-7	none	N	n/a	n/a	normal care
Jasper	6.5-7	sometimes dyed to imitate other stones	D	o	e	normal care
Sard	6.5-7	heated to produce color	E/H	u	e	normal
Sard	6.5-7	dyed to produce color	D	o	g-e	certain stones may fade in light or heat
^ Top
Chrome Diopside	5-6	none	N	n/a	n/a	moderately soft, avoid sudden temperature changes, harsh chemicals
Chrome Tourmaline - see Tourmaline
^ Top
Chrysoberyl
Cat's Eye	8.5	none	N	n/a	n/a	normal
Cat's Eye	8.5	irradiated to change color	R	o	e	normal
Brown, Yellow, Green	8.5	none	N	n/a	n/a	normal
^ Top
Coral
Black	3-4	none	N	n/a	n/a	special - avoid chemicals, cosmetics and ultrasonic
White	3-4	bleached	E/B	c	g	special - avoid chemicals, cosmetics and ultrasonic
Pink	3-4	impregnated with colorless wax	E/W	c	g	special - avoid chemicals and ultrasonic
Orange	3-4	stabilized with plastic to improve color and durability	I	c	g	special - avoid chemicals and ultrasonic
Gold	3-4	bleached from black coral	B	c	v-g	avoid chemicals and ultrasonic
Red	3-4	dyed	D	u	v	special to extra special depending on type of dye - avoid chemicals, cosmetics and ultrasonic
Corundum - see Sapphire / Ruby				o
^ Top
Danburite
White	7-7.5	none	N	n/a	n/a	normal care
Brown	7-7.5	irradiated	R	c	g	*Research in Progress
Demantoid - see Garnet
^ Top
Diamond
Diamond	10	none	N	n/a	n/a	normal
Diamond	10	laser drilled to improve appearance	L	o	v-g	normal
Colorless to Faint Yellow	10	coated to disguise off color	C	r	p-vg	color may be affected by polishing, recutting, ultrasonic, alcohol and harsh chemicals
Colorless to Faint Yellow	10	fracture filled to improve clarity	F	o	v-g	avoid extreme heat and recutting
Colorless to Faint Yellow	10	heat pressure treated	HP	r	u	normal
Colored	10	use of heat to alter color	H	r	u	normal
Colored	10	laser drilled to improve appearance	L	o	v-g	normal
Colored	10	irradiated and/or heated to produce a variety of colors	R	o	e-vg	normal
Colored	10	fracture filled to improve clarity	F	r	v-g	avoid extreme heat and recutting
Green	10	Irradiated and/or heated to produce green	R	o	e-vg	special care - avoid heating, color may change
^ Top
Diaspore	6.5-7	none	N	n/a	n/a	normal
^ Top
Diopside	5-6	none	N	n/a	n/a	moderately soft, avoid sudden temperature changes, and harsh chemicals
Dravite - see Tourmaline
Emerald - see Beryl
^ Top
Feldspar
Amazonite	6-6.5	impregnated with colorless wax, paraffin or oil	E/W	u	f-g	avoid extreme heat, harsh chemicals and ultrasonic
Amazonite	6-6.5	impregnated with hardened resins	I	u	v-g	avoid chemicals and ultrasonic
Labradorite / Spectrolite	6-6.5	none	N	n/a	n/a	*Research in Progress
Moonstone	6-6.5	none	N	n/a	n/a	normal
Orthoclase	6-6.5	none	N	n/a	n/a	*Research in Progress
Plagioclase	6-6.5	none	N	n/a	n/a	*Research in Progress
Sunstone	6-6.5	none	N	n/a	n/a	*Research in Progress
Fire Agate - see Chalcedony
^ Top
Fluorite
Colorless/ Colored	4	none	N	n/a	n/a	soft, avoid harsh chemicals
Blue, Green, Purple	4	irradiated to produce color	R	u	u	soft, avoid harsh chemicals
^ Top
Garnet
Almandite	7-7.5	none	N	n/a	n/a	normal - avoid sudden temperature change
Demantoid	6.5-7	none	N	n/a	n/a	normal
Grossular	7-7.5	none	N	n/a	n/a	normal
Hessonite	7-7.5	none	N	n/a	n/a	normal
Pyrope	7-7.5	none	N	n/a	n/a	normal
Rhodolite	7-7.5	none	N	n/a	n/a	normal
Spessartite (Mandarin)	7-7.5	none	N	n/a	n/a	normal
Topazolite	6.5-7	none	N	n/a	n/a	normal
Tsavorite	7-7.5	none	N	n/a	n/a	normal
Uvarovite	7-7.5	none	N	n/a	n/a	normal
Goshenite - see Beryl	7.5-8
Green Tourmaline - see Tourmaline
^ Top
Hematite	5.5-6.5	none	N	n/a	n/a	normal
Hessonite - see Garnet
Hiddenite - see Spodumene
^ Top
Howlite
White	3.3-5	none	N	na	n/a	*Research in Progress
Blue	3-3.5	dyed to imitate turquoise	D	c	g	Very soft, avoid harsh chemicals, ultrasonic, and steaming
Hyacinth - see Zircon
Indicolite - see Blue Tourmaline
^ Top
Iolite	7-7.5	none	N	n/a	n/a	normal
^ Top
Ivory
Ivory / Bone	2-3	bleached to whiten and remove discoloration	E/B	c	g	very soft, avoid chemicals and ultrasonic, may discolor with time
Ivory / Bone	2-3	dyed for artistic purposes	D	o	g	very soft, avoid chemicals and ultrasonic, may discolor with time
Ivory / Bone	2-3	impregnated with colorless paraffin wax	W	o	g	very soft, avoid chemicals and ultrasonic, may discolor with time
Ivory / Mammoth	2-3	impregnated with colorless hardened substances to increase stability	I	c	g	normal
^ Top
Jade
Jadeite	6.5-7	coated with colorless wax	E/W	c	f	avoid ultrasonic and harsh chemicals
Jadeite	6.5-7	bleached and wax impregnated	B/W	r	p	avoid heat, harsh chemicals and ultrasonic
Jadeite(Green, White, Purple)	6.5-7	bleached and polymer impregnated	B/I	c	g-vg	avoid heat, harsh chemicals and ultrasonic
Jadeite (Green, White, Purple)	6.5-7	dyed to imitate natural colors	D	o	v	avoid strong light, chemicals and ultrasonic
Nephrite	6-6.5	dyed	D	r	u	avoid strong light, harsh chemicals and ultrasonic, may discolor with time
^ Top
Kornerupine
Kornerupine	6.5-7	none	N	n/a	n/a	*Research in Progress
Cat's Eye Kornerupine	6.5-7	none	N	n/a	n/a	*Research in Progress
^ Top
Kyanite	4-7	none	N	n/a	n/a	very soft in certain directions
Kunzite - see Spodumene
Labradorite - see Feldspar
^ Top
Lapis Lazuli
Lapis Lazuli	5-6	coated with wax or oil	E/W	c	f	avoid chemicals and ultrasonic
Lapis Lazuli	5-6	dyed to produce color or uniformity in color	D	c	v	avoid chemicals and ultrasonic
^ Top
Malachite
Malachite	3.5-4	coated with colorless wax	W	o	f	soft, avoid chemicals and ultrasonic
Malachite	3.5-4	impregnated with plastic and/or other hardened agents	I	r	g	soft, avoid chemicals and ultrasonic
Mandarin Garnet - see Spessartite
^ Top
Marcasite	6-6.5	none	N	n/a	n/a	normal
Maxixe - see Beryl
^ Top
Moldavite	5.5	none	N	n/a	n/a	normal
Moonstone - see Feldspar
Morganite - see Beryl
Moss Agate - see Chalcedony	6.5-7
Nephrite - see Jade
Oligoclase - see Feldspar
Olivine - see Peridot
^ Top
Opal
White, Black, Semi-Black	5.5-6.5	natural	N	n/a	n/a	avoid excessive heat / ultrasonic
White, Black, Semi-Black	5.5-6.5	impregnated with colorless oil, wax and resins	O	r	f	avoid excessive heat, solvents and ultrasonic
White, Black, Semi-Black	5.5-6.5	impregnated with colorless plastic to improve durability and color	I	r	g	avoid excessive heat and solvents
Boulder	5.5-6.5	infusion of unhardened colorless substances to improve appearance	O	o	f	avoid heat, chemicals, ultrasonic and repolishing
Cat's Eye Opal	5.5-6.5	impregnated with colorless plastic to improve durability and color	I	u	g	avoid heat, chemicals, and ultrasonic
Fire Opal	5.5-6.5	none	N	n/a	n/a	avoid heat
Hydrophane	5.5-6.5	impregnated with colorless oil, wax and resins	O	c	f	avoid heat and solvents
Hydrophane	5.5-6.5	impregnated with colorless plastic to improve durability and color	I	c	g	avoid heat and solvents
Hydrophane	5.5-6.5	dyed	D	c	g	avoid heat and solvents
Matrix	5.5-6.5	sugar solution infilling in acid bath to darken background	D	c	g	avoid heat, solvents and repolishing
Orthoclase - see Feldspar
Padparadscha - see Sapphire
Paraiba Tourmaline - see Tourmaline
^ Top
Pearl
Natural	2.5-4.5	bleached to improve color and appearance	B/E	u	vg	special care - avoid cosmetics and household chemicals
Natural	2.5-4.5	dyed with or without chemical treatment combined with heat to produce gray to black	D	r	g-vg	special care - avoid cosmetics and household chemicals and ultrasonic
Cultured	2.5-4.5	bleached to improve color and uniformity of white color only	B/E	u	e	special care - same as above
Cultured	2.5-4.5	dyed to give rose, blue or golden overtones	D	u	g	special care - same as above
Cultured	2.5-4.5	dyed blue, black and other colors includes use of colored nuclei	D	o	v	special care - same as above
Cultured	2.5-4.5	dyed all colors (freshwater)	D	u	vg	special care - same as above
Cultured	2.5-4.5	irradiated to produce blue, gray, black and bronze colors	R	o	vg	special care - same as above
Cultured	2.5-4.5	chemical treatment combined with heat to produce gray to black	D	c	g-vg	special care - same as above
Mabe	2.5-4.5	color coated, dyed, bleached, filled with a hardened substance and a MOP back. Sometimes coating can be plastic or polymer to protect the thin nacre	B/D/I (ASBL)	a	f-vg	extra special care - avoid household chemicals, cosmetics, abrasives, and sudden shocks
^ Top
Peridot
Peridot	6.5-7	none	N	n/a	n/a	normal care
Peridot	6.5-7	impregnated with colorless oil, wax and resins	E/O	r	f-g	avoid sudden temperature changes, harsh chemicals and ultrasonic
Peridot	6.5-7	surface fracture filling with a colorless hardened substance	F	r	g	avoid sudden temperature changes, harsh chemicals and ultrasonic
^ Top
Petalite	6-6.5	*Research in Progress	*	*	*	*Research in Progress
^ Top
Phenakite	7.5-8	*Research in Progress	*	*	*	normal care
^ Top
Petrified Wood	6.5-7	none	N	n/a	n/a	normal care
^ Top
Pietersite	7	none	N	n/a	n/a	normal care
Pink Tourmaline - see Tourmaline
^ Top
Pyrite	6-6.5	none	N	n/a	n/a	avoid harsh chemicals and excessive heat
Pyrope - see Garnet	7-7.5
^ Top
Quartz
Amethyst	7	none	N	n/a	n/a	may fade with long exposure to sunlight
Amethyst	7	heated to improve color	H	r	e	avoid exposure to high heat
Ametrine	7	none	N	n/a	n/a	normal care
Aventurine	7	none	N	n/a	n/a	normal care
Black	7	irradiated to alter color	R	u	g-e	normal care
Citrine	7	heated to improve color	E/H	u	e	normal care
Ginger	7	irradiated to alter color	R	a	e	normal care
Lilac	7	heated to improve color	H	o	e	normal care
Oro Verde	7	irradiated and heated to produce color	R	a	e	normal care
Smoky	7	irradiated to alter color	R	u	g	normal care
Rock (Colorless)	7	none	N	n/a	n/a	normal care
Rose	7	natural	N	n/a	n/a	normal care
Tourmalinated	7	none	N	n/a	n/a	normal care
Rutilated	7	none	N	n/a	n/a	normal care
Tiger's Eye	7	bleached, dyed or heated	B/D/H	o	g-vg	avoid harsh chemicals, ultrasonic and steaming
Violet	7	heated to improve color	H	o	g-e	normal care
Watermelon	7	heated to improve color	H	o	g-e	normal care
^ Top
Rhodochrosite	3.5-4	none	N	n/a	n/a	very soft
Rhodolite - see Garnet
^ Top
Rhodonite	5.5-6	dyed to make color uniform	D	o	p	special care - avoid chemicals and ultrasonic
Rubellite-see Tourmaline (Red)
^ Top
Ruby
Ruby	9	natural	N	n/a	n/a	normal care
Ruby	9	heated to improve color and clarity	E/H	u	g-e	normal care
Ruby	9	irradiated to change color	R	r	u	normal care
Ruby	9	intentional filling of surface cavities and fractures	F/Fh	c	f-vg	avoid caustic acids, extreme pressure, heat and ultrasonic
Ruby	9	surface or lattice (bulk) diffusion penetrating most/all of the stone	U	o	g	special care - avoid repolishing/recutting
Ruby	9	dyed with colored oil to improve appearance	D	r	p	special care - avoid harsh chemicals and ultrasonic
Star Ruby	9	surface diffusion of color or asterism	U	o	g	special care - avoid repolishing/recutting
Star Ruby	9	heated to improve color/asterism	E/H	c	g-e	normal care
^ Top
Sapphire
Sapphire	9	natural	N	n/a	n/a	normal care
Sapphire	9	heated to improve color/clarity	E/H	u	e	normal care
Sapphire	9	surface or lattice (bulk) diffusion penetrating most/all of the stone	U	o	g	special care - avoid repolishing/recutting
Sapphire	9	irradiation to produce temporary yellow or orange color	R	o	vp	extra special - fades quickly in light or heat
Star Sapphire	9	surface diffusion of color or asterism	U	o	g	special care - avoid repolishing/recutting
White (Colorless)	9	heated to improve color/clarity	E/H	u	g-e	normal care
Black Star	9	heated	E/H	u	vg	normal care
Fancy Colors (Green, Orange, Purple, Pink, Padparadscha, Yellow)	9	surface or lattice (bulk) diffusion penetrating most/all of the stone	E/H	c	f-g	special care - avoid repolishing/recutting
^ Top
Scapolite
Yellow	5.5-6	none	N	n/a	n/a	avoid ultrasonic cleaners and exposure to strong sunlight
Violet	5.5-6	*Research in Progress	*	*	*	*Research in Progress
^ Top
Serpentine
Serpentine	2.5-5.5	dyed	D	c	f-g	color may fade
Serpentine	2.5-5.5	impregnated with colorless wax	E/W	c	g-vg	avoid ultrasonic, chemicals and solvents
^ Top
Shell	4	dyed	D	c	f-g	avoid harsh chemicals
^ Top
Sinhalite	6.5-7	*Research in Progress	*	*	*	*Research in Progress
^ Top
Sodalite	5.5-6	dyed	D	r	f	color may fade
^ Top
Sphalerite	3.5-4	none	N	n/a	n/a	very soft stone, generally not suited for jewelry use
Spessartite - see Garnet
^ Top
Sphene	5-5.5	none	N	n/a	n/a	normal care, best used in earrings & pendants due to softness
^ Top
Spinel (all colors)	8	none	N	n/a	n/a	normal care
^ Top
Spodumene
Kunzite	6.5-7	irradiated & heated	R	c	f	avoid strong light/ultrasonic
Kunzite	6.5-7	heated to improve color	E/H	c	f	color may fade in strong light/sunlight, avoid ulltrasonic
Hiddenite (Green)	6.5-7	none	N	n/a	n/a	color fades in light or heat
Hiddenite (Green)	6.5-7	irradiated to produce green color	R	r	p	extra special care - color fades in light or heat
Yellow	6.5-7	irradiated to produce yellow color	R	r	p	extra special care - color fades in light or heat

Sugulite	6-6.5	none	N	n/a	n/a	normal care
Sunstone - see Feldspar
Tanzanite - see Zoisite
Tiger's Eye - see Quartz
^ Top
Topaz
Blue	8	irradiated and/or heated to produce blue color	R	u	e	normal care
Brown	8	none	N	n/a	n/a	may fade with exposure to sunlight
Brown	8	irradiated	R	o	p	will fade
Green	8	irradiated to improve the color	R	o	p	extra special care - color fades in exposure to sunlight
Green	8	diffusion of color at or near the surface	U	u	g	special care - avoid repolishing or recutting
Mystic, Ocean, Glacier, Patriot, Canary, Champagne, Orchid, Dawn, Teal, Kiwi (others)	8	enhanced with various coatings to produce a variety of colors (chemical vapor deposition)	C	a	f	avoid harsh chemicals, heat, ultrasonic cleaners and repolishing/recutting
Pink/Red	8	heated chromium-bearing pinkish-brown to orange stones	E/H	u	e	normal care
Yellow / Orange	8	irradiated to intensify color	R	o	v	special care - avoid heat and strong light
White	8	none	N	n/a	n/a	normal care
^ Top
Taaffeite	8-8.5	none	N	n/a	n/a	normal care
^ Top
Tourmaline
Cat's Eye	7-7.5	none	N	n/a	n/a	normal care
Chrome	7-7.5	none	N	n/a	n/a	normal care
Green, Blue	7-7.5	none	N	n/a	n/a	normal care
Green, Blue	7-7.5	heated to improve color	E/H	c	e	normal care
Green, Blue	7-7.5	the penetration of colorless oils / unhardened resins	O	o	f-g	avoid steaming, chemicals, ultrasonic, and temperature changes
Paraiba	7-7.5	heated to improve color	E/H	c	g-vg	normal care
Pink, Red, Purple	7-7.5	heated to improve color	E/H	o	e	normal care
Pink, Red, Purple	7-7.5	irradiated to intensify color	R	c	g	normal care
Pink, Red, Purple	7-7.5	penetration of colorless oils or unhardened resins into fissures to improve appearance	O	o	f-g	special care - avoid temperature changes, steaming, chemicals and ultrasonic
Pink, Red, Purple	7-7.5	penetration of coloring agents into voids to improve appearance	D	o	p-f	special care - avoid temperature changes, steaming, chemicals and ultrasonic
Yellow / Orange	7-7.5	heated to improve color	E/H	r	e	normal care
Yellow / Orange	7-7.5	irradiated to improve color	R	r	vg	normal care
Tsavorite - see Garnet
^ Top
Turquoise
Turquoise	5-6	impregnated with plastic to create or improve color and increase durability	I	c	g	special care - avoid hot water, household chemicals, and ultrasonic
Turquoise	5-6	impregnated with colorless oil or wax to enhance or create color	W	c	p-f	special care - avoid hot water, household chemicals, and ultrasonic
Turquoise	5-6	dyed to improve color	D	r	p	special care - avoid hot water, harsh household chemicals, and ultrasonic
^ Top
Unakite	6-7	none	N	n/a	n/a	avoid harsh chemicals
^ Top
Variscite	4-5	none	N	n/a	n/a	may fade in strong light
Verdelite - see Green Tourmaline
Yellow Beryl - see Beryl
^ Top
Zircon
Blue, Colorless	6.5-7	brownish crystals are heated to improve these colors	E/H	a	p-f	special care - avoid harsh abrasives and strong light
Green / Brown	6.5-7	none	N	n/a	n/a	special care - avoid harsh abrasives
Red	6.5-7	heated to change brownish crystals to red	E/H	c	p-f	special care - avoid harsh abrasives
Yellow	6.5-7	heated to improve color	E/H	r	g-f	special care - avoid harsh abrasives
^ Top
Zoisite
Tanzanite	6.5-7	heated to produce violet/blue color	E/H	u	e	special care due to hardness

*Research in Progress Complete information regarding the possible enhancement/special care on this gem is currently being researched due to the rarity of this stone in the jewelry trade. Our sources include, but are not limited to, university mineralogical, gemological, geology departments, as well as gem laboratories, the Internet, and individual experts in the trade. Updates will be made as more information becomes available. Gemstone Enhancement Codes (based on AGTA guidelines)
^ Top
B=Bleaching The use of heat, light and/or chemicals or other agents to lighten or remove a gemstone's color. This is often accompanied by subsequent dying and/or impregnation. Example: bleached cultured pearl; bleached/impregnated jadeite ('B-jade)
^ Top
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. Example: coated diamond, coated topaz
^ Top
D=Dyeing (Staining) The introduction of coloring matter into a gemstone to give it new color, intensify existing color or improve color uniformity. Example: dyed green jadeite
^ Top
E=Normally Enhanced The "E" symbol is used for gemstones that are routinely enhanced. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, our approach is to assume that such enhancements have been applied to that particular gemstone. This assumption is made to protect both buyer and seller. If a more specific method of enhancement is known, then the specific enhancement code will be used.
^ Top
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 weight. Example: ruby
^ Top
Fh=Flux healing During heat enhancement, fluxes (or heat alone) may be used to heal fractures/fissures which were formerly open. The process dissolves the walls of the fractures and redeposits the molten gem material, healing the fractures closed. Example: ruby (particularly that from Mong Hsu, Burma)

Gemstone Enhancements and Treatments

*Research in Progress

B=Bleaching

C=Coating

D=Dyeing (Staining)

E=Normally Enhanced

F=Filling

Fh=Flux healing