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      Gemstone Enhancements, Treatments & Care


    Gemstone Enhancements, Treatments & Care

    Skillfully merging art and science, a variety of techniques are used to help gemstones reach their full potential. As critical as good cutting, enhancements and treatments are an integral part of the modern gemstone industry. With its roots in antiquity (e.g. heat treatment has been practiced in India for over 4,000 years), most of the techniques used simply facilitate the beautiful end results of the earth’s natural processes. Below are some answers to common gemstone enhancement, treatment and care questions.

    Is the use of enhancements and treatments globally accepted?

    With close to 99% of the more popular gem types enhanced, as long as they are disclosed, all permanent enhancements and treatments are globally accepted. As the majority of gemstones traded internationally have undergone some form of enhancement, always assume treatments when purchasing gemstones.

    Are all enhancements and treatments permanent?

    With the exception of Emeralds, whose beauty is enhanced by the application of oils or polymers, Thaigem.com only knowingly accepts enhancements and treatments that are permanent with normal wear. Our information sources for gem enhancements and treatments includes university mineralogical, gemological and geology departments, gem laboratories, trade associations, regulatory bodies, professional journals, books, the internet, and individual experts.

    Do enhancements or treatments affect a gem’s value?

    For some varieties there is no difference between the values of enhanced, treated or natural gemstones. However, high quality unheated Rubies and Sapphires are extremely rare and command a much higher market price. When attempting to purchase Rubies and Sapphires, please be aware that unheated/untreated specimens are almost non-existent, and as a result, always purchase from a reliable supplier or have the seller’s claim verified by a gemologist.

    How do I care for my gemstone jewelry?

     Caring for your gemstone jewelry (i.e. Normal care) is a matter of common sense and simple precaution. For gemstone specific care instructions, please refer to the table below.

    • Always remove your jewelry when engaging in activities that risk impact or exposure to chemicals or heat such as sports or housework.
       

    • Always put jewelry on after using cosmetics, hair spray or perfumes, not before.
       
    • Never remove your jewelry by pulling on the gems.
       

    • Carefully wipe jewelry with a soft lint free cloth after each wearing to remove oils and salts.
       

    • Once in a while, take the time to clean your jewelry. Always clean your jewelry with a cleaning solution or mechanical cleaner suitable for the gem.

    What are mechanical cleaners?
    The most common mechanical cleaners are ultrasonic and steam cleaners. Ultrasonic cleaners feature two basic parts; a small motor and a cleaning tank. The machine’s motor produces ultrasonic energy that is transmitted with vibrating energy waves (usually 40,000 sound waves per second) to create microscopic bubbles in the cleaning tank. Called cavitation, this motion knocks dirt off the jewelry and is very effective in penetrating the tiny crevices in jewelry that traditional cleaning cloths and topical cleaners cannot easily reach. A steam cleaner uses jets of steam to literally blast dirt off jewelry. As some gemstones can be damaged by mechanical cleaners, check the table below to see if your gemstone is suitable.

     How are gemstones enhanced or treated?

    Below are the enhancements and treatments used for some popular gemstones, their purpose, frequency and care:
     
    GEMSTONE HARDNESS TREATMENT EXPLANATION CARE STEAM CLEANING ULTRASONIC CLEANING
    AGATE 6.5 - 7 Dyed or heated. Used to alter color, these treatments are usually applied. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    AGATE (DENDRITIC, FIRE, IRIS & MOSS) 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    ALEXANDRITE 8.5 Colorless oils, wax and resins in fissures. Used to improve appearance, these treatments are rarely used. Normal care. Yes. No.
    AMAZONITE 6 - 6.5 Colorless wax or oil, paraffin or hardened resins and/or impregnated with colorless plastic or hardened resins. Used to improve appearance, colorless wax or oil is usually applied while impregnation with colorless plastic or hardened resins is occasionally applied. Normal care.  Yes. No.
    AMBER 2 - 2.5 Dyed, surface treated or heated. Used to improve appearance and/or to deepen color, dying and surface treatments are rarely applied while heating is usually applied. Normal care. Coated gemstones are not suitable for re-cutting or re-polishing. No. No.
    AMBYGLONITE 5.5 - 6 Not treated. N/A Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. Yes. No.
    AMETHYST 7 Heated. Used to lighten color and/or to remove smokiness, this treatment is only occasionally applied. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    AMETHYST (GREEN) 7 Heated or irradiated. This treatment provides/improves color and appearance and is usually applied. Normal care. Yes. No.
    AMETRINE 7 Heated. Rarely used to improve color. Normal care. Yes. No.
    AMMOLITE 4 Impregnated with colorless hardened substances. This treatment is commonly used to increase stability. Normal care. Coated gemstones are not suitable for re-cutting or re-polishing. Yes. No.
    ANATASE 5.5 - 6 Not treated. N/A N/A N/A N/A
    ANDALUSITE 7 - 7.5 Not treated. N/A Normal care. Yes. No.
    ANDESINE 6 - 6.5 Not treated. N/A Normal care.  Yes. No.
    ANGLESITE 2 - 3 Not treated. N/A Very fragile, handle with care. N/A N/A
    APATITE 5 Heated. Usually applied, this treatment improves appearance and/or deepens color. Normal care. No. No.
    APOPHYLLITE 4.5 - 5 Not treated. N/A Very fragile, handle with care. No. No.
    AQUAMARINE 7.5 - 8 Heated. Used to remove yellow components to produce a purer blue color this treatment is usually applied. Normal care. Yes. No.
    ARAGONITE 3.5 - 4 Not treated. N/A Normal care.  Yes. No.
    AVENTURINE (BLACK) 7 Irradiated. Usually applied, this treatment is used to change the color. Normal care. Yes. Yes.
    AXINITE 6 - 7 Not treated. N/A Normal care. Yes. No.
    AZURITE 3.5 - 4 Surface colorless waxing and/ or impregnated with colorless oil, wax or resin. Used to improve appearance, surface colorless waxing is commonly applied while impregnation with colorless oil, wax or resin is rarely applied. Normal care. Yes. No.
    AZURMALACHITE (AZURITE MALACHITE) 3.5 - 4 Surface waxing and/or impregnated with colorless plastic or hardened resin. Used to improve stability, durability, luster and/or color, surface waxing is commonly applied while impregnation with colorless plastic or hardened resin is rarely applied. Normal care. Yes. No.
    AZURITE (DRUZY) 3.5 - 4 Not treated. N/A N/A N/A N/A
    BARITE 2.5 - 3.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    BASTNAESITE 4 - 4.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    BIXBITE 7.5-8 Colorless oil and resin. This treatment is commonly used to improve appearance. Normal care. No. No.
    BLOODSTONE 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    BORACITE 7 - 7.5 Not treated. N/A N/A N/A N/A
    BRAZILIANITE 5.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    BURBANKITE 3.5 - 4 Not treated. N/A Very fragile, handle with care. N/A N/A
    BUSTAMITE 3.32 - 3.43 Not treated. N/A Very fragile, handle with care. N/A N/A
    CALCITE 3 Not treated. N/A Very fragile, handle with care. Yes. No.
    CASSITERITE 6 - 7 Not treated. N/A Normal care. Yes. No.
    CELESTITE 3 - 3.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    CHALCEDONY (BLUE & GREEN) 6.5 - 7 Dyed. This treatment is commonly used to improve color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. Yes.
    CHAROITE 6 Not treated. N/A Normal care. Yes. No.
    CHRYSOBERYL (BROWN, GREEN, YELLOW) 8.5 Not treated. N/A Normal care. Yes. No.
    CHRYSOBERYL  (CAT’S EYE) 8.5 Irradiated. Uncommonly applied, this treatment is used to change color and to improve Chatoyancy. Normal care. Yes. No.
    CHRYSOCOLLA 2 - 4 Surface colorless waxing and/or impregnation with colorless plastic or hardened resin. Used to improve appearance, these treatments are occasionally applied. Normal care. Yes. No.
    CHRYSOPRASE 6.5 - 7 Not treated. N/A Normal care. Yes. Yes.
    CINNABAR 2 - 2.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    CITRINE 7 Heated or irradiated. Usually applied, this treatment produces color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    CLINOHUMITE 6 Not treated. N/A N/A N/A N/A
    CORNELIAN 6.5 - 7 Heated and/or dyed. Used to produce color, heating is usually applied while dying is occasionally applied. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    CREEDITE 4 N/A N/A N/A N/A N/A
    DANBURITE (WHITE) 7 – 7.5 Not treated. N/A Normal care. Yes. No.
    DANBURITE (BROWN) 7 - 7.5 Irradiated. Commonly applied to improve appearance. Normal care. Yes. No.
    DATOLITE 5 - 5.5 Not treated. N/A Normal care. Yes. No.
    DIAMOND (COLOR TREATED) 10 Irradiated. The process known as color treatment involves using clean Diamonds and modifying their color with a combination of electron bombardment and heat using safe electron-accelerator technology. This process exactly duplicates the natural exposure of Diamond crystals to radioactive elements during their formation. Used to improve color intensity or to produce unique colors, this treatment is always applied. Normal care. Yes. Yes.
    DIAMOND 10 Laser drilled. This is occasionally used to improve appearance. Normal care. Yes. Yes.
    DIAMOND (WHITE TO FAINT YELLOW) 10 Coated, pressure heated and fractured filled. Used to disguise off color, Coating are rarely applied. Fracture filling is occasionally applied to improve clarity and pressure heating is rarely applied to improve clarity. Normal care. Coated gemstones are not suitable for re-cutting or re-polishing. Yes. No.
    DIASPORE 6.5 - 7 Not treated. N/A Normal care.  Yes. No.
    DIOPSIDE 5 - 6 Not treated. N/A Normal care.  Yes. No.
    DOLOMITE 3.5 - 4 Not treated. N/A N/A N/A N/A
    DUMORTIERITE 7 - 8.5 Not treated. N/A Normal care. Yes. No.
    EKANITE 6 - 6.5 N/A N/A N/A N/A N/A
    EMERALD 7.5 - 8 Colorless oils, polymers, wax, resins in fissures and/or dyed with the use of colored oils and/or open fractures or cavities filled with hardened resins.  These treatments improve appearance. Colorless oils, polymers, wax, resins in fissures are usually applied. Dying with the use of colored oils is occasionally applied. Open fractures or cavities filled with hardened resins are commonly applied. Normal care. Periodically, enquire if they need to be re-oiled.  No. No.
    ENSTATITE 5 - 6 Not treated. N/A Normal care.  Yes. No.
    EOSPHORITE 5 Not treated. N/A N/A N/A N/A
    EPIDOTE 6 - 7 Not treated. N/A Normal care.  Yes. No.
    EUCLASE 7.5 Not treated. N/A Normal care.  Yes. No.
    EUDIALYTE 5.5 Not treated. N/A N/A N/A N/A
    FIRE BERYL? 7.5 - 8 Not treated. N/A Normal care. Yes. No.
    FLUORITE (BLUE, GREEN & PURPLE) 4 Irradiated or heated. Commonly applied, this treatment provides color. Normal care. Yes. No.
    FLUORITE (WHITE) 4 Not treated. N/A Normal care. Yes. Yes.
    FOSSILS N/A Not treated. N/A N/A N/A N/A
    GAHNITE 7.5 - 8 Not treated. N/A Normal care. Yes. No.
    GARNET 7 - 7.5 Not treated. N/A Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    GENTHELVITE 6 - 6.5 N/A N/A N/A N/A N/A
    GLACIER TOPAZ? 8 Not treated. N/A Normal care. No. No.
    HAUYNE 5 - 6 Not treated. N/A N/A N/A N/A
    HELIODOR (CAT’S EYE) 7 – 7.5 Not treated. N/A Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. Yes.
    HELIODOR 7 - 7.5 Irradiated. Usually applied, this treatment provides color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. Yes.
    HEMATITE 5.5 - 6.5 Not treated. N/A Normal care. Yes. No.
    HEMIMORPHITE 5 Not treated. N/A N/A N/A N/A
    HERDERITE 5 - 5.5 Not treated. N/A N/A N/A N/A
    HIDDENITE 6.5 - 7 Irradiated. Rarely used, this treatment improves and/or provides color and uniformity. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    HOWLITE (BLUE) 3 - 3.5 Dyed. Commonly used, this treatment is used only when imitating Turquoise. Normal care. No. No.
    HOWLITE (WHITE) 3 - 3.5 Not treated. N/A N/A N/A N/A
    IDOCRASE 6.5 Not treated. N/A Normal care. Yes. No.
    IOLITE 7 - 7.5 Not treated. N/A Normal care. Yes. Yes.
    JADEITE (JADE) 6.5 - 7 Colorless polymer impregnation and/or polymer and colorless polymer impregnation followed by acid treatment and/ or dyed. Commonly applied, this treatment improves color and uniformity. Normal care. Yes. No.
    JASPER 6.5 - 7 Dyed. Commonly applied, this treatment is used to imitate other gemstones. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    JASPER (MULTI-COLORED) 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    KORNERUPINE 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    KUNZITE (GREEN & CAT’S EYE) 6.5 - 7 Not treated. N/A Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    KUNZITE 6.5 - 7 Heated or irradiated. Commonly applied, this treatment improves and/or darkens color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    KYANITE 4 - 7 Not treated. N/A Normal care. Yes. No.
    LABRADORITE 6 - 6.5 Surface colorless waxing. Occasionally applied to improve appearance. Normal care.  Yes. No.
    LAPIS LAZULI 5 - 6 Surface colorless waxing and/or dyed. Commonly applied, this treatment is used to provide color and/or color uniformity. Normal care. Yes. No.
    LARIMAR 5 Not treated. N/A N/A N/A N/A
    LEIFITE 6 N/A N/A N/A N/A N/A
    MAGNESITE 3.5 - 4 Not treated. N/A N/A Yes. Yes.
    MALACHITE 3.5 - 4 Surface colorless waxing and/or impregnated with colorless plastic or hardened resin. These treatments are used to improve the gem’s color. Surface colorless waxing and/or coating with colorless wax are occasionally applied. Impregnation with colorless plastic or hardened resin is rarely applied. Normal care. Yes. No.
    MAMMOTH IVORY 2 - 3 Impregnated with colorless plastic or hardened resins and/or colorless surface waxing and/or dyed and/or bleached. These treatments are commonly used to increase stability. Impregnation with colorless plastic or hardened resins and bleaching are commonly applied. Colorless surface waxing and dying are occasionally applied. Normal care. No. No.
    MANGANOTANTALITE 6 - 6.5 Not treated. N/A N/A N/A N/A
    MARCASITE 6 - 6.5 Not treated. N/A Normal care. Yes. Yes.
    MAWSITSIT 6 - 8 Not treated. N/A Normal care. Yes. No.
    MELLITE 2 - 2.5 N/A N/A Very fragile, handle with care. N/A N/A
    MILARTE 5.5 - 6 N/A N/A N/A N/A N/A
    MOLDAVITE 5.5 - 6.5 Not treated. N/A Normal care. Yes. Yes.
    MONAZITE 5 - 5.5 Not treated. N/A N/A N/A N/A
    MONTEBRASITE 5.5 - 6 Not treated. N/A Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    MOOKITE 6.5 N/A N/A N/A N/A N/A
    MOONSTONE 6 - 6.5 Not treated. N/A Normal care.  Yes. No.
    MORGANITE 7.5 - 8 Heated. Commonly applied, this treatment eliminates yellow overtones. Normal care. Yes. No.
    MORGANITE (GREEN) 7.5 - 8 Cobalt heated. Always applied, this treatment induces vivid green color. Normal care. Yes. No.
    NATROLITE 5 - 5.5 Not treated. N/A N/A Yes. Yes.
    NEPHRITE 6.5 - 7 Dyed and/or impregnated with colorless oil, wax or resin. Rarely used, this treatment improves color and uniformity. Normal care. Yes. No.
    NEPHRITE (CAT’S EYE) 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    NUUMMIT 5 - 6 Not treated. N/A Normal care. Yes. No.
    OBSIDIAN 5.5 - 7 Not treated. N/A Normal care. Yes. No.
    OLIGOCLASE 6 - 6.5 Not treated. N/A Normal care.  Yes. No.
    ONYX 6.5 - 7 Dyed. Always applied, this treatment is used to achieve color uniformity. Normal care. Yes. Yes.
    OPAL (BLACK, SEMI-BLACK & WHITE) 5.5 - 6 Impregnated with colorless oils, waxes, plastic or resins. Used to improve durability, appearance and color, this treatment is rarely applied.  Normal care. Some gemstones are prone to crack due to loss of structural water. Keep away from heat and drying environments. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    OPAL (BOULDER) 5.5 – 6 Infusion of unhardened colorless substances into voids. Used to improve appearance, this treatment is occasionally applied. Normal care. Some gemstones are prone to crack due to loss of structural water. Keep away from heat and drying environments. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    OPAL (CAT’S EYE) 5.5 – 6 Impregnated with colorless plastic. Used to improve durability and color, this treatment is usually applied. Normal care. Some gemstones are prone to crack due to loss of structural water. Keep away from heat and drying environments. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    OPAL (FIRE & MOSS) 5.5 – 6 Not treated. N/A Normal care. Some gemstones are prone to crack due to loss of structural water. Keep away from heat and drying environments. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.

     

    PARISITE 4.5 N/A N/A N/A N/A N/A
    PEARL (CULTURED) 2.5 - 4.5 Bleached, dyed or chemically treated. Occasionally used, these treatments improve color and uniformity. Clean either by wiping gently with a moist cloth or rinsing and gently patting dry with a soft cloth. No. No.
    MOTHER OF PEARL 2.5 - 4.5 Coated, dyed or bleached. Occasionally used, these treatments improve color and uniformity. Clean either by wiping gently with a moist cloth or rinsing and gently patting dry with a soft cloth. No. No.
    PECTOLITE 4.5 - 5 Not treated. N/A N/A N/A N/A
    PERIDOT 6.5 - 7 Heat, colorless oil, wax or resins in fissures and/ or filled fractures with colorless hardened resin. Used to improve appearance, this treatment is rarely applied. Rarely heated to oxidize specific minerals to enhance color. . Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    PETALITE 6 - 6.5 N/A N/A N/A N/A N/A
    PEZZOTTAITE 8 Not treated. N/A Normal care. No. No.
    PHENAKITE 7.5 - 8 Not treated. N/A. Normal care. Yes. Yes.
    POLLUCITE 6.5 - 7 Not treated. N/A N/A N/A N/A
    PRASIOLITE 7 Heated. This treatment improves color and appearance and is usually applied. Normal care. Yes. No.
    PREHNITE 6 - 6.5 Not treated. N/A Normal care. Yes. No.
    PYRITE 6 - 6.5 Not treated. N/A Normal care. Yes. No.
    PYROXMANGITE 5.5 - 6 Not treated. N/A N/A N/A N/A
    QUARTZ 7 Heated, irradiated or coated. Occasionally applied, this treatment improves color or produces unique colors. Normal care. Gemstones with superficial color (or phenomena) surface layers are not suitable for re-cutting or re-polishing. Yes. No.
    QUARTZ (BLUE MOON) 7 Heated. This treatment provides/improves color and appearance and is usually applied. Normal care. Yes. No.
    QUARTZ (CAT’S EYE, RUTILATED & ROSE) 7 Not treated. N/A Normal care. Yes. No.
    QUARTZ (SMOKY) 7 Irradiated. Used to alter color, this treatment is occasionally applied. Normal care. Yes. No.
    QUARTZITE 7 Dyed and/or impregnated with colorless plastic or hardened resins. Used to improve appearance, this treatment is occasionally applied. Normal care. Yes. No.
    REMONDITE 3 - 3.5 Not treated. N/A N/A N/A N/A
    RHODOCHROSITE 7 Not treated. N/A Normal care. Yes. No.
    RHODONITE 7 Dyed. Used for color uniformity, this treatment is occasionally applied. Normal care. Yes. No.
    RUBY 9 Heated and/or the healing of fissures and/or glass filled open fractures and cavities and/or lead glass filled open fractures and cavities and/or dyed and/or bulk diffusion of certain elements during the heating process and/or colorless oil or resin in fissures. Usually applied, these treatments produces, intensifies or lightens color and/or improves color uniformity and or appearance. Examples of the additives used include beryllium (i.e. light element) to permanently improve color and borax or lead (i.e. glass) to permanently improve appearance. Normal care. Fillers in voids/cavities, fissures and/or open fractures can scratch more easily than the host gem or be more vulnerable to damage from heat or some chemicals. Yes. Yes.
    SAPPHIRE 9 Heated and/or the healing of fissures and/or glass filled open fractures and cavities and/or lead glass filled open fractures and cavities and/or dyed and/or bulk diffusion of certain elements during the heating process and/or colorless oil or resin in fissures. Usually applied, these treatments produces, intensifies or lightens color and/or improves color uniformity and or appearance. Examples of the additives used include beryllium (i.e. light element) to permanently improve color and borax or lead (i.e. glass) to permanently improve appearance. Normal care. Fillers in voids/cavities, fissures and/or open fractures can scratch more easily than the host gem or be more vulnerable to damage from heat or some chemicals. Yes. Yes.
    SARD 6.5 - 7 Dyed or heated. This treatment is used to provide color. Heating is usually applied while dying is occasionally applied. Normal care. Yes. No.
    SARDONYX 6.5 Dyed. Usually used, this treatment improves color. Normal care. Yes. No.
    SCAPOLITE (YELLOW) 5.5 - 6 Not treated. N/A Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    SCAPOLITE (VIOLET) 5.5 - 6 N/A N/A N/A N/A N/A
    SCHEELITE 4.5 - 5 Not treated. N/A N/A N/A N/A
    SCOLECITE 5 - 5.5 Not treated. N/A N/A N/A N/A
    SELLAITE 5 - 6 Not treated. N/A N/A N/A N/A
    SENARMONTITE 2 - 2.5 Not treated. N/A Very fragile, handle with care. N/A N/A
    SERANDITE 4.5 N/A N/A N/A N/A N/A
    SHELL (PINK) 4 Dyed. Often applied to improve color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    SHORTITE 3 Not treated. N/A N/A N/A N/A
    SIDERITE 4 Not treated. N/A N/A N/A N/A
    SILLIMANITE 6 - 7 Not treated. N/A Normal care. Yes. No.
    SINHALITE 6.5 - 7 Not treated. N/A Normal care. Yes. No.
    SMITHSONITE 4 - 5 Not treated. N/A Normal care. Yes. No.
    SODALITE 5.5 - 6 Dyed. Rarely applied, this treatment is used to improve color. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    SPECTROLITE 6 - 6.5 Surface colorless waxing. Occasionally applied to improve appearance. Normal care.  No. No.
    SPHALERITE 3.5 - 4 Not treated. N/A Normal care. Very fragile, handle with care. Yes. No.
    SPHENE 5 - 5.5 Not treated. N/A Normal care. Yes. No.
    SPINEL 8 Not treated. N/A Normal care. Yes. No.
    STAUROLITE 7 - 7.5 Not treated. N/A N/A N/A N/A
    SUGILITE 6 - 6.5 Not treated. N/A Normal care.  Yes. No.
    SUNSTONE 6 - 6.5 Not treated. N/A Normal care.  Yes. No.
    TANOLITE? 7 - 7.5 Not treated. N/A Normal care. Yes. No.
    TANZANITE 6.5 - 7 Heated. Usually applied, this treatment produces the colors for which this gem is known. Usually applied. Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    THAUMASITE 3.5 N/A N/A N/A N/A N/A
    TIGER’S EYE 7 Dyed, bleached or heated. Used to improve color, these treatments are commonly applied. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    TIGER’S EYE (VIOLET) 7 Heated. This treatment is occasionally applied to improve the color. Normal care. Yes. Yes.
    TITANIUM (DRUZY) 7 Titanium Coated. This treatment changes the surface of the gem permanently into a rainbow effect. Normal care. No. Yes.
    TOPAZ (EXCEPT WHITE) 8 Irradiated, heated, coatings and/or diffused. Used to improve color intensity or to produce unique colors, these treatments are usually applied. Physical Vapor Deposition (PVD) coating involves the application of a bonded layer of fine titanium atoms (USA Patent Number 5,853,826 for Azotic Coating Technologies Inc.). When this oxide treatment falls within a certain thickness, optical interference produces a variety of colors. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Gemstones with superficial color (or phenomena) surface layers are not suitable for re-cutting or re-polishing. No. No.
    TOURMALINE 7 - 7.5 Heated and/or irradiated and/or filling of colorless oils, resins and waxes in fissures and/or cavities fractures filled with colorless hardened substances. Used to improve color intensity and appearance these treatments are commonly applied. Normal care. Yes. No.
    TOURMALINE (CAT’S EYE, CHROME, BI-COLORED, PARTY & WATERMELON) 7 - 7.5 Not treated. N/A Normal care. Yes. No.
    TREMOLITE 5 - 6 Not treated. N/A Normal care. Yes. No.
    TUGTUPITE 4 Not treated. N/A Normal care. Yes. No.
    TURQUOISE 5 - 6 Impregnated with plastic and/or surface colorless waxing and/or dyed. These treatments improve stability, durability, luster and/or color. Impregnation with plastic and surface colorless waxing are commonly applied. Dying is rarely used. Normal care. Yes. No.
    UNAKITE 6 - 7 Not treated. N/A Normal care. Yes. Yes.
    VESUVIANITE 6.5 Not treated. N/A Normal care. Yes. No.
    VILLIAUMITE 2 - 2.8 Not treated. N/A N/A N/A N/A
    WILLEMITE (BLUE) 5.5 Heated. This treatment is used to change the color from white to blue. Normal care. Some gemstones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes. No. No.
    WILSONITE 3 - 4 Not treated. N/A N/A N/A N/A
    WULFENITE 2.28 - 2.4 Not treated. N/A Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    ZIRCON (BLUE,  RED, WHITE & YELLOW) 6.5 - 7 Heated. Used to improve color this treatment is always applied. Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.
    ZIRCON (BROWN & GREEN) 6.5 - 7 Not treated. N/A Normal care. Some gemstones fade or revert to their original color when exposed to strong light. Do not wear or leave them for extended periods under these conditions. Yes. No.

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