Privacy Policy

Enhancements & Disclosures

ALEXANDRITE (Chrysoberyl): none known
Variety or trade name: cat’s-eye alexandrite, cymophane

AMBER: heating in oil, heating, dyeing
Variety or trade name: block, Baltic, sea, pit, clear, fatty, cloudy, foamy, bone, Sicilian, Burmese, Roumanian, pressed, Dominican, Bernstein, gedanite, chemawinite, sun-spangled

AMETHYST (Quartz ): heat treatment
Trade names: Uralian or Siberian, ametrine / amethyst-citrine / trystine / golden

AMMONITE: lacquer coating
Variety or trade name: ammolite, korite, aapaok, calcentine

ANDALUSITE: heating
Variety or trade name: viridine, chiastolite

AQUAMARINE (Beryl): heat treatment
Variety or trade name: Madagascar, Brazilian

APATITE: no commercial treatment known
Variety or trade name: Cat’s-eye apatite, asparagus

AZURITE: impregnation with paraffin or epoxy resin
Variety or trade name: chessy copper, chessylite, azure stone

BENITOITE: none known

BERYL: (other than emerald and aquamarine) — heating, irradiation plastic coating
Variety or trade name: Green, golden, morganite, goshenite, cat’s-eye beryl, star, Maxixe, red

CALCITE: dyeing
Variety or trade name: Iceland spar, marble, onyx marble, satinspar

CASSITERITE: none known
Variety or trade name: tin stone, tin ore, wood tin, toad’s eye tin

CITRINE (Quartz ): heat treatment
Trade names: topaz quartz

CHALCEDONY: dyeing
Variety or trade name: milky, chrysoprase, carnelian, bloodstone (heliotrope), prase, agate, moss agate, landscape agate, onyx, sard, sardonyx, carnelian onyx, jasper, plasma, chysocolla chalcedony/quartz, petrified — agatized — silicified wood, iris agate, fire agate, dendritic agate, amethystine chalcedony

CHRYSOBERYL: (other than phenomenal varieties) — none known
Variety or trade name: cymophane (cat’s-eye)

CLINOHUMITE: none known

COPAL: any treatment used for amber can be used for copal
Variety or trade name: kauri gum, baby amber (trade name)

CORAL (calcareous): dyeing, impregnation with epoxy or glue-like materials
Variety or trade name: angel’s skin, bianco, rosa pallido, rosa vivo, rosso, rosso scuro, carbonetto, ox blood, Japanese, tosa, moro, Italian, Sardinian, Sicilian, Algerian

EMERALD (Beryl): oiling (oil may contain green dye)
Variety or trade name: Colombian, Trapiche, Russian or Siberian, Brazilian, Sandawana, Zambian

FANCY SAPPHIRE (corundum): heating followed by controlled cooling, diffusion (heating above 1900°C in the presence of coloring agents), coating with a thin film, heating, irradiation (various types)
Variety or trade name: golden, padparadscha, hyacinth, green, amethystine, or rose, color change, white, adamantine spar

CUPRITE: none known

DANBURITE: none known

DIAMOND: irradiation, coating, laser drilling and bleaching, filling cracks on stones of low clarity
Variety or trade name: canary, champagne, jonquil, coffee, cape, river, jager, premier, piqué, chameleon

DIOPSIDE: none known
Variety or trade name: star diopside, cat’s-eye diopside, malacolite, alalite, violane, chrome

EUCLASE: irradiation

FELDSPAR ORTHOCLASE: blue or black coating on back
Variety or trade name: moonstone or adularia

FELDSPAR PLAGIOCLASE: heat diffusion
Variety or trade name: andesine, spectrolite (trade name for labradorite), sunstone (variety of labradorite or oligoclase)

FLUORITE: plastic or epoxy resin impregnation, irradiation, heating
Variety or trade name: blue john

GARNET ALMANDITE: heat
Variety or trade name: star almandite (or star garnet)

MALAIA AND COLOR CHANGE GARNETS: none known

GARNET RHODOLITE: none known

GARNET SPESSARTITE: none known

IOLITE: none known
Variety or trade name: dichroite, bloodshot iolite

JADEITE JADE: dyeing, often preceded by heating to "open pores", colorless impregnation, especially with paraffin, heating
Variety or trade name: Imperial — gem — emerald jade, apple green, chloromelanite, Uynan jade, moss-in-snow, fei-ts’ui or kingfisher jade

NEPHRITE JADE: dyeing, impregnation with paraffin wax, heating
Variety or trade name: New Zealand greenstone — jade or spinach jade, mutton fat, chicken bone, tomb or grave jade

KORNERUPINE: none known

KYANITE: none known

LAPIS LAZULI: dyeing, paraffin coating or impregnation, oiling
Variety or trade name: Persian or Afghan, Russian or Siberia, Chilean

MALACHITE: impregnation with paraffin or epoxy resin
Variety or trade name: peacock stone

OPAL: impregnation with oil, wax or plastic, treatment with aniline dye, silver nitrate, or sugar carbonized by acid, backing with reflective foil, black paint, etc.
Variety or trade name: white, black, semiblack or gray, crystal, black crystal, fire, cherry, jelly or water, noble or precious.
Names based on play-of-color: pinfire/pinpoint, harlequin/mosaic, flame, flash, peacock, lechoses.
Less common names: contra-luz, boulder, matrix, Louisiana, opalized bone/wood/shell, oolitic, Tabasheer.
Common: common, milk, onyx, wax, moss, cachalong/kalmuck agate, girasol, hyalite, hydrophane, wood, iron.

PEARL: bleaching, dyeing
Variety or trade name: pink, white, cream rosè, black, colored, Oriental, Ceylon or Madras, Tahiti, South Seas, Burma, island, Venezuela, Australian, La Paz, maiden, blister, dust, seed, baroque, freshwater, Bombay, fancy, hinge, half

PERIDOT: no commercial treatments known Chrysolite, Hawaiite

QUARTZ: (other than amethyst, citrine and chatoyant varieties) — quench-crackling (heating and then cooling quickly), irradiation, heat treatment, coating or foil on back of cabochon, dyeing
Variety or trade name: rock, smoky, rose, aventurine, iris or rainbow, rutilated, sagenitic, dumortierite, milky, gold, star, green, quartzite, tourmalinated

RHODOCHROSITE: none known

RHODONITE: none known

RUBY (corundum): heating followed by controlled cooling, heating above 1900°C in the presence of titanium oxide or other coloring agents), oil and dye, glass filling in cavities and cracks.
Variety or trade name: Burma or Oriental, beef blood, French-color, cherry, Thai or Siamese, Ceylon or Sri Lankan, African, star

SAPPHIRE (BLUE) (corundum): heating followed by controlled cooling, diffusion heating above 1900°C in the presence of coloring agents, coating with a thin film
Variety or trade name: Kashmir or Cashmere, Burma or Oriental, Thai or Siamese, Ceylon or Sri Lankan, Montana, African, Australian, gueda

STAR RUBY & STAR SAPPHIRE (corundum): heating and slow cooling, diffusion (heating above 1900°C in the presence of titanium oxide), oil and dye
Variety or trade name: black star sapphire

SCAPOLITE: irradiation

SCHEELITE: none known

SHELL: dyeing
Variety or trade name: helmut, conch, operculum, mother of pearl

SINHALITE: none known

SMITHSONITE: none known
Variety or trade name: bonamite

SPHALERITE: none known
Variety or trade name: cleiophane, marmatite

SPHENE: none known
Variety or trade name: chrome sphene

SPINEL: none known
Variety or trade name: flame, color change, star, ceylonite or pleonaste

SPODUMENE: irradiation
Variety or trade name: kunzite, hiddenite, triphane

TAAFFEITE: none known

TOPAZ: heating, irradiation
Variety or trade name: sherry, hyacinth, imperial, precious

TOURMALINE: (Variety or trade name: chrome tourmaline / Paraiba) — heating, irradiation, acid treatment, sealing tubes with a plastic or epoxy filler
Variety or trade name: rubellite, verdelite, indicolite, dravite, achroite, schorl, parti-colored, watermelon, cat’s-eye, color change, chrome, Paraiba

TURQUOISE: plastic impregnation, sometimes with a coolant added, wax impregnation, dyeing with liquid black shoe polish, backing thin pieces with an epoxy
Variety or trade name: Persian, American or Mexican, Egyptian, spiderweb

The Zachery Treated Turquoise: method is named after its developer, James E. Zachery, an electrical engineer and active trader of turquoise.

This is a proprietary enhancement method, the specifics of which are not public.  The method can only be used on turquoise that is of moderate quality.  The turquoise is soaked in a non-toxic, secret chemical brew.  When dried, the stone is easier to polish and the colors may be slightly more vivid.   The only way to determine if a stone has been treated with this method is by destroying it and subjecting it to a chemical analysis.  In a study by Fritsch et al., published in Gems and Gemology, it is reported that turquoise that has been treated with the Zachery method has more potassium than natural turquoise.  What other chemicals might be used in the process is unknown.

This method is regarded highly by many in the trade because it is largely undetectable, even through the eyes of an expert; leads to a stone with greater luster; and does not involve the use of dyes and hardening agents.  However, since it does not strengthen the stone in any substantial way, its use is restricted to good quality turquoise.

ZIRCON: heat treatment
Variety or trade name: high and medium, low (metamict), hyacinth or jacinth, jargon or jargon, beccarite, melichrysos, sparklite, starlite and stremlite

ZOISITE: heating
Variety or trade name: tanzanite, thulite, ruby in zoisite