::Colored gemstones - Treatments & enhancement processes

Colored gemstones - Treatments & enhancement processes

Colored gemstones - commercial wax filler.

The history of treating gemstones with a variety of methods to improve their appearance goes back thousands of years. Today, gemstones are commonly treated to improve their color, clarity and/or durability. These treatments are various, common and acceptable in the industry as long as disclosure of the treatment is made to the buyer. It is estimated as many as 99% of rubies, sapphires and emeralds are treated, and verified un-treated examples in finer qualities command a premium price over the treated varieties.

Many popular gem types are treated, and all permanent techniques are universally accepted, again, as long as disclosure of the treatment is made to the buyer. Please note that the term "natural gemstones" refers to those formed in the earth, whether or not they have been treated after mining. These are distinctly different from "lab created", "man made" or "synthetic" gems which must be clearly labeled as "man made materials" and not "natural gemstones" according to Federal Trade Commission (FTC) law. Gemstones which are a combination of natural and manmade materials must be declared as "assembled stones".

Gemstone types	Treatments and benefits	Care instructions
Agate (see Chalcedony)	Routinely heated, bleached or dyed to improve color	Normal care
Alexandrite	Not routinely enhanced	Normal care
Almandite (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Amazonite	Impregnated with wax, oil, plastic or colorless hardened resins to stabilize and improve appearance	Avoid heat, household chemicals and ultrasonic
Amber	Routinely heated or dyed to deepen or add color	Avoid chemicals, steam and ultrasonic cleaning
Amethyst (Quartz)	Routinely heated and/or irradiated to improve color	Normal care
Ammonite (Ammolite)	Impregnated with colorless hardened resins to stabilize and improve appearance	Avoid heat, household chemicals and ultrasonic
Ametrine (Quartz)	Routinely heat- treated to improve color	Normal care
Andalusite	Occasionally heat-treated to improve color	Normal care
Apatite	Occasionally heated to improve color	Avoid chemicals, steam and ultrasonic cleaning
Aquamarine (Beryl)	Routinely heated to improve color	Normal care
Aventurine (Quartz)	Occasionally dyed to improve color	Normal care
Azurite	Occasionally filled with epoxy or resin to stabilize and improve surface appearance	Avoid chemicals, steam and ultrasonic cleaning
Azure-malachite	Rarely filled with epoxy or resin for smoother surface and improve durability	Avoid chemicals, steam and ultrasonic cleaning
Bixbite (red beryl)	Routinely oiled or resin treated to improve clarity	Avoid heat, household chemicals and ultrasonic
Topaz	Usually irradiated and heated to produce color	Normal care but avoid sudden temperature changes
Canary Aqua ™	Routinely irradiated to enhance color	Normal care but avoid excessive heat.
Cat's Eye Chrysoberyl	Rarely irradiated to darken color	Normal care
Chalcedony	Routinely heat-treated, bleached and dyed to induce different colors	Normal care
Chrome Diopside	Not routinely enhanced	Avoid chemicals and sudden temperature changes
Chrysoberyl transparent varieties (yellow, green, brown)	Not routinely enhanced	Normal care
Chrysoprase	Not routinely enhanced	Normal care
Citrine (Quartz)	Routinely heat-treated to improve color	Normal care
Coral	Routinely dyed, bleached and/or impregnated with wax, plastic or resin to improve color and stability	Avoid chemicals, steam and ultrasonic cleaning
Demantoid (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Diamond - colorless	Occasionally laser drilled and then filled with lead glass to improve clarity. Occasionally fracture filled with lead glass to improve clarity. Occasionally HTHP treated to improve color	Normal care
Diamond - colored	Often irradiated to improve color	Normal care
Emerald (Beryl)	Routinely oiled or resin treated to improve clarity	Avoid chemicals, steam and ultrasonic cleaning
Fluorite	Routinely heated and/or irradiated to improve color	Avoid chemicals, steam and ultrasonic cleaning
Garnet (also listed by type)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Gaspeite	Occasionally stabilized with plastic	Normal care
Goshenite	Not routinely enhanced	Normal care
Heliodor	Irradiated to improve color	Normal care
Hematite	Not routinely enhanced	Normal care
Hessonite (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Howlite	Routinely dyed to improve color and to emulate turquoise	Avoid steam and ultrasonic cleaning
Indicolite (Tourmaline)	Routinely heat-treated to improve color	Normal care but avoid sudden temperature changes
Iolite	Not routinely enhanced	Normal care but avoid sudden temperature changes
Jadeite	Type “A” Not routinely enhanced in higher qualities. Lower grades routinely filled with wax to reduce visibility of cracks and improve surface appearance Type “B” Routinely bleached and dyed. Routinely filled with wax to reduce visibility of cracks	Normal care
Jasper	Occasionally dyed to enhance color	Normal care
Jet	Not routinely enhanced	Avoid steam and ultrasonic cleaning
Kornerupine	Not routinely enhanced	Normal care but avoid rough handling
Kunzite (Spodumene)	Occasionally heated and/or irradiated to enhance color	Avoid sudden temperature changes, rough handling and exposure to strong light.
Kyanite	Not routinely enhanced	Avoid rough handling, steam and ultrasonic cleaning
Labradorite	Not routinely enhanced	Avoid rough handling, steam and ultrasonic cleaning
Lapis Lazulli	Routinely dyed, wax or resin impregnated to improve color and luster	Avoid chemicals, steam and ultrasonic cleaning
Lepidolite	Not routinely enhanced	Normal care
Malachite	Occasionally dyed, wax or resin impregnated to improve color uniformity and surface appearance	Avoid chemicals, steam and ultrasonic cleaning
Mariposite	Not routinely enhanced	Normal care
Moldavite	Not routinely enhanced	Normal care
Moonstone	Not routinely enhanced	Normal care
Morganite (Beryl)	Routinely heated and/or irradiated to enhance color	Normal care
Mother of Pearl	Routinely dyed to produce a wide variety of colors	Avoid chemicals, steam and ultrasonic cleaning
Muscovite	Not routinely enhanced	Normal care
Onyx (Chalcedony) Black Onyx	Routinely heat-treated, irradiated, bleached and dyed to induce different colors Always dyed	Normal care
Opal	Occasionally oil, wax or resin treated to hide cracks and provide stability. “Matrix” variety commonly treated with sugar and acid depositing carbon in pore spaces significantly darkening the stone	Avoid chemicals, steam and ultrasonic cleaning
Pearl	Routinely bleached, dyed and/or irradiated to improve or induce color	Avoid chemicals (including hairspray and cosmetics), steam and ultrasonic cleaning
Peridot	Not routinely enhanced	Avoid chemicals, steam and ultrasonic cleaning, sudden temperature changes
Petalite	Not routinely enhanced	Avoid rough handling, ultrasonic cleaning
Petrified Wood (see Chalcedony)	Occasionally bleached and heated to improve color	Normal care
Pietersite	Not routinely enhanced	Normal care
Pyrope (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Rainbow Calsilica	An artificial material created for carving/lapidary purposes.	Avoid chemicals, steam and ultrasonic cleaning
Rhodochrosite	Not routinely enhanced	Avoid chemicals, rough handling, and excessive heat.
Rhodolite (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Rhodonite	Occasionally dyed to even color	Normal care
Rosenite™ (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Rubellite (Tourmaline)	Routinely heated and/or irradiated to improve color	Normal care but avoid sudden temperature changes
Ruby	Routinely heated to improve color and/or clarity. Occasionally diffusion heat treated with chemicals to improve color. Often clarity enhanced with borax and/or lead glass to fill fissures and fractures. Occasionally enhanced by a combination of these treatments.	Normal care
Rutilated Quartz	Not routinely enhanced	Normal care
Sapphire	Routinely heated to improve color and/or clarity. Occasionally diffusion heat treated with chemicals to improve color. Occasionally clarity enhanced with borax and/or lead glass to fill fissures and fractures, and occasionally enhanced by a combination of these treatments.	Normal care
Scapolite	Routinely irradiated for color enhancement	Avoid steam and ultrasonic cleaning, avoid exposure to strong light
Serpentine	Routinely dyed and/or impregnated with wax to improve appearance and enhance colors	Avoid steam and ultrasonic cleaning
Shell	Commonly dyed to produce a wide variety of colors	Avoid chemicals, steam and ultrasonic cleaning
Smokey Quartz	Routinely heat-treated or irradiated to improve color	Normal care
Sodalite	Not routinely enhanced	Avoid chemicals, steam and ultrasonic cleaning
Spessartite (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Sphene	Not routinely enhanced	Avoid chemicals, sudden temperature changes, and rough handling
Spinel	Not routinely enhanced	Normal care
Sugilite	Not routinely enhanced	Avoid steam and ultrasonic cleaning
Sunstone	Not routinely enhanced	Avoid chemicals, steam and ultrasonic cleaning
Tanzanite	Routinely heated to remove brown tones and purify , violet- or violet colors	Avoid steam, ultrasonic cleaning and sudden temperature changes
Tiger Iron	Not routinely enhanced	Normal care
Tiger's Eye (Quartz)	Routinely heat-treated, dyed or bleached to enhance color	Avoid sudden temperatures changes and strong chemicals
Topaz (other than )	Routinely heated to enhance colors	Normal care but avoid sudden temperature changes
Tourmaline	Greens and s routinely heat-treated to enhance color.	Normal care but avoid sudden temperature changes
Tsavorite (Garnet)	Not routinely enhanced	Normal care but avoid sudden temperature changes
Turquoise	Routinely stabilized (impregnated) with plastic or resins to enhance durability and color, and occasionally dyed	Avoid chemicals, steam and ultrasonic cleaning. Perspiration and cosmetics may alter color.
Unakite	Not routinely enhanced	Avoid chemicals, steam and ultrasonic cleaning
Variscite	Occasionally stabilized (impregnated) with plastic or resins to enhance durability and color, and occasionally dyed	Avoid chemicals, steam and ultrasonic cleaning
Verdelite (Tourmaline)	Routinely heated to improve color	Normal care but avoid sudden temperature changes
White Aqua™ (Beryl)	Routinely heated to remove faint color	Normal care
Yellow Beryl (Heliodor)	Routinely heated and/or irradiated to improve color	Normal care but avoid excessive heat
Zircon	Routinely heat-treated to induce color and improve yellows and reds	Avoid abrasives, rough wear and exposure to strong light.

Various Other Treatments:

Bleaching: Use of chemicals to lighten or remove a gem's color.

Coating: Use of surface treatments such as films, lacquers, etc. to provide color or other special effects.

Dyeing: The introduction of coloring matter into a gem to give it a new color or greater intensity.

Filling: Introduction of colorless borax, lead glass or other substances into cracks through heating.

Gamma/Electron Radiation: The use of gamma or electron irradiation for the purpose of changing a gem's color, may be followed by a heating process to stabilize the color. Such stones do not exhibit residual radioactivity.

Heating: The use of heat to clarify, change color or create phenomena in gems.

Infilling: The intentional filling of surface breaking cracks and cavities with a foreign material such as synthetic resins with hardeners (Opticon), glass or plastic.

Lasering: The use of a laser to drill into a stone and remove or alter an inclusion, refers most often to diamonds.

Oiling or Resin Infusion: The intentional filling of surface breaking cavities and cracks in transparent or translucent gems with a colorless oil, wax, resin or man-made unhardened resin.

Irradiation: The use of neutron bombardment to alter color. This process creates residual radioactivity and such stones must receive a Nuclear Regulatory Commission safety release prior to sale. Usually used in combination with other radiation and or heating treatments.

Bonding: The intentional use of a colorless bonding agent (usually plastic) within a porous gemstone.

Diffusion: The use of specific chemicals during a high temperature heating process for the purpose of penetrating the surface layer (usually to a slight depth only) with coloring or star-making chemicals.

Waxing/Oiling: The impregnation of colorless wax, oil or paraffin into porous opaque gems to improve appearance.

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