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171 Cards in this Set
- Front
- Back
What is the most common habit of an emerald?
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An elongated six-faced prism, sometimes with striations along its length
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What are the most desirable emerald colors?
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Bluish green to green, with strong to vivid saturation and medium to meduim dark tone.
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What stone has the finest green color?
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Emerald
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What is the finest emerald color?
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Columbian
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what word is used to describe emeralds that are slightly darker and more bluish than Columbian emeralds, often with higher clarity?
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Zambian
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What describes emeralds that are commonly a bright, intense green?
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Sandawana emeralds. They are usually smaller than Columbian emeralds.
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What describes the lightest color of emeralds?
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Brazilian.
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Where do Columbian emeralds form?
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Hydrothermal deposits.
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What crystal has 6-faced prisms?
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Emeralds
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What are the cut considerations for an emerald?
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Almost all emeralds have significant fractures and insignificant cleavages. They can be quite brittle.
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What is "jardin"?
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Emerald inclusions that look mossy or garden-like.
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What is used to fill emerald's fractures?
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Oil or resin or a mixture of both.
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What is the safest way to clean emeralds?
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Gently scrub with warm, soapy water.
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Japan and US account for what percent of emerald purchases worldwide?
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75 Per cent
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Most emeralds come from what 4 countries?
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Columbia
Zambia Brazil Zimbabwe |
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What makes Sandwana emeralds small yet richly colored?
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High chromium and low iron.
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What is the most common imitator of the emerald?
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Synthetic spinel triplets.
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What methods are used to synthesize emeralds?
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Hydrothermal and flux.
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What is a trapiche emerald?
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An emerald that has rays that emanate from a hexagonal center.
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What is Coscuez?
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One of Columbia's traditional emerald mines.
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What emerald mine had its first significant production in 1998-1999?
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La Pita
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Who produced a hydrothermal sythetic emerald layered over faceted beryl?
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Lechleitner.
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What is a pearl?
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A pearl is an organic gem produced by a living organism.
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When does pearl formation start?
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When a foreign object gets inside a pearl-bearing mollusk's shell and irritates its soft tissue.
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What is a natural pearl?
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One that forms without human assistance.
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What is a cultured pearl?
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A pearl formed as the result of human intervention in the formation process.
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What is nacre?
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The natural substance produced by pearl-bearing mollusks to make pearls.
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What is argonite?
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A crystallized form of calcium carbonate found in nacre.
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What is conchiolin?
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The organic "glue" in nacre that holds argonite platelets together.
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What is mother-of-pearl?
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The nacreous layer inside a pearl-bearing mollusk's shell.
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What is "calcareous concretion"?
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A non-nacreous natural"pearl"
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What are the 2 best know non-nacreous pearls?
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Conch "pearls"
Melo "pearls" |
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What is a cultured blister pearl?
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A cultured pearl grown around a nucleus glued under the mantle tissue inside a mollusk's shell.
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What is mantle?
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The organ that lines the mollusk's shell, encloses its soft body, and contains the cells that form pearl sacs and secrete nacre.
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What contributed to the decline of the pearl industry?
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Pearl culturing, plastic buttons, and oil drilling
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What is a bead nucleus?
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A bead made from a freshwater mussel shell, used as the core of a cultured pearl.
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What is a bead nucleus?
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A bead made from a freshwater mussel shell, used as the core of a cultured pearl.
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What is a mantle-tissue piece?
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A small square of mantle tissue cut from a donor mollusk and implanted in a host mollusk with or without a bead.
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What is the gonad?
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The reproductive organ that produces eggs in females and sperm in males.
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What is a pearl sac?
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Tissue that encloses an implanted bead nucleus and mantle-tissue piece, or the piece alone, and secretes nacre to form a cultured pearl.
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What are the 4 types of cultured pearls?
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Akoya
South Sea Tahitian freshwater |
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What is akoya?
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Common name for the Pinctada fucata oyster and the natural or cultured pearls that the oyster produces.
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What is the average size of a South Sea pearl?
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13mm.
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Where are South Sea pearls produced?
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Australia, Phillipines, and Indonesia
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Where are Tahitian pearls from?
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French Polynesia
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What is the average size of a Tahitian pearl?
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9.5mm
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What size are freshwater pearls?
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Between 4 mm and 11mm.
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When did Chinese freshwater pearls appear in the market?
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1970's
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What country produces the majority of freshwater cultured pearls?
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China
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What is the rarest and most valuable cultured pearl shape?
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Round
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What gives a pearl its unique beauty?
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Luster.
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How many categories are there of luster?
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4:
Excellent good fair poor |
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What is essence d'orient?
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A mixture of clear varnish and fish scales used in making imitation pearls.
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What are Jadeite's 3 most important qualities?
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Color
transparency texture |
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What is the most valuable jadeite color?
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Vivid green known as Imperial.
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What is old mine?
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The finest texture category of jadeite.
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what is relatively old mine?
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The medium texture category of jadeite.
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What is new mine?
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The coarsest texture category of jadeite.
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Where is the main polishing center for jadeite?
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China
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What is a hololith?
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Gemstone jewelry carved entirely from a single piece of rough.
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What is Type A jadeite?
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Natural jadeite enhanced only with wax.
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What is type B jadeite?
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Natural jadeite that's bleached in acid to remove undesirable staining, then impregnated with wax or polymers.
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What is type c jadeite?
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Natural jadeite that's dyed and sometimes bleached and impregnated with wax or polymers.
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What is river jade?
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Weathered, thin-skinned jadeite boulders.
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What is mountain jade?
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Thick-skinned jadeite boulders.
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what is nephrite made of?
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Nephrite is made up of fibrous crystals that interlock in a matted tufted texture.
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Where does black jade come from?
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Guatemala.
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What are some substitutes for jade?
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Crysoprase chalcedony
Californite idocrase hydorgrossular garnet |
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What opal gets the highest price of all opals?
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Black opal.
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What color opal makes up the bulk of commercial-quality opal on the market?
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white opal.
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What makes boulder opal more durable than other types of boulder?
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Matrix backing
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What type of opal is cut as a faceted gemstone?
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Fire opal.
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What is the most desirable play-of-color hue?
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REd.
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Where does 90 percent of the world's opal supply come from?
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Australia
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What opal is mined only in the state of Queensland in northeastern Australia?
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Boulder opal.
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Where is the major source of fire opal?
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Mexico
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What is a slocum stone?
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An opal imitation made of glass that appeared in the late 1970's.
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What is an agate?
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Chalcedony with curved or angular bands or layers that differ in color and transparency.
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Where is the major source of the finest quality of amethyst?
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Africa.
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Where is the most prolific source of commercial quality amethyst?
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Brazil
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Where is the source of natural ametrine?
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Bolivia.
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What is sagenitic quartz?
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Transparent quartz, usually rock crystal, that contains eye-visible inclusions, often named according to the type of inclusion it contains.
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Wht is rutilated quartz?
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A type of quartz containing needle-like rutile inclusions.
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What is tourmalinated quartz?
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A type of sagenitic quartz containing needle-like or rod-like tourmaline inclusions.
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What is botryoidal?
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A crystal growth habit with a bumpy appearance similar to a bunch of grapes.
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In crysoprase, the green hue comes from?
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Nickel.
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What is the most valuable chalcedony varieties?
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Chrysocolla chalcedony
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Where is chrysocolla found?
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US and Mexico
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What is sard?
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A warm hued calcedony that is semitransparent to translucent. but darker and less saturated than carnelian.
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What is onyx and sardonyx?
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Banded varieties of chalcedony that show straight, parallel stripes of contrasting colors.
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Where is tsavorite mined?
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East Africa
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Demantoid is colored by?
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Chromium and iron.
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Where is demantoid from?
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Russia and Africa
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What is hessonite?
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Hessonite is the tranparent orange to cinnamon colored variety of the species grossularite.
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What is the most valuable red garnet?
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Rhodolite
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Where is rhodolite mined?
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East Africa.
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In spinel, what makes the red hue?
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Chromium
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What is the most valuable spinel hue?
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Red
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Spessartite is most commonly found in?
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Pegmatite veins
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Which species of garnet has the widest color range?
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Grossularite
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Tsavorite and hessonite are both varieties of?
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Grossularite
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All garnets have the same?
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Crystal structure
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Rhodolite is a mixture of?
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Pyrope and almandite
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What is isomorphous replacement?
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The substitution of one chemical element for another in the crystal structure of a mineral.
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Mandarin garnet is a trade name for?
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spessartite garnet.
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Horsehair inclusion are found in ?
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Demantoid.
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What is malaya?
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A trade term used for a pinkish orange garnet that's a mixture of pyrope, spessartite and almandite
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What is an elbaite?
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A tourmaline that is rich in sodium, lithium and aluminum
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Most gem tourmalines form in?
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Pegmatites.
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the worl'd largest producer of tourmaline is?
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Brazil.
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the worl'd largest producer of tourmaline is?
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Brazil.
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The most expensive variety of tourmaline is?
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Paraiba
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Paraiba tourmaline is colored by?
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copper
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What trade term is used for blue tourmaline?
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Indicolite.
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Who is the largest producer of chrome tourmaline?
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Tanzania
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Rubellite tourmaline is colored by?
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Manganese
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Many green and blue tourmalines are lightened by?
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heating
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Many Paraiba tourmalines are?
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heated.
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the cause of color in peridot is?
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Iron
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Most of the commercial quality peridot is mined?
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Arizona
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The color of blue zircon is due to?
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Heat treatment
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Metamict zircons are:
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low zircons
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What countries produce the finest peridot?
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Myanmar and Pakistan
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What is the color of Imperial topaz?
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reddish orange to orange-red
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What is the most valuable topaz variety?
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Pink and red
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Most gem quality topaz comes from?
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pegmatites
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The term precious topaz is used for?
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Yellow to orange stones.
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What is the most common color of untreated natural topaz?
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colorless
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The major source of Imperial topaz is?
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Brazil
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In order to attain a treated pink color, yellow to reddish brown topaz must contain?
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chromium
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The finest aquamarine color is?
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Medium dark blue to slightly greenish blue
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What method is used to produce synthetic aquamarine?
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Hydrothermal
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The most important source of aquamarine is?
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Brazil
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Which recent source is the leading producer of small, commercial-quality aquamarine?
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China
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Most aquamarine has its color improved by?
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heat treatment
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What color is morganite beryl?
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Pink
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Which is the rarest beryl?
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Red beryl
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The only source of red beryl is?
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Utah
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Spodumene, feldspar, and diopside have how many cleaveage directions?
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Two
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What 3 basic elements do all feldspars contain?
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aluminum, oxygen and silicon
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Moonstone is a variety of?
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Orthoclase
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When did moonstone go out of style?
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Art Deco
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The adularescence of the finest moonstones is?
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Blue
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Tiny tension cracks in moonstones are called?
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centipedes.
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Rainbow moonstone is a trade term for a type of?
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Labradorite
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Spectrolite is a variety of?
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Labradorite
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The greenish blue feldspar that has gridlike white streaks and resembles turquoise is?
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amazonite
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What color is hiddenite?
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Medium green
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Kunzite's most common color is?
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Pink
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Light-colored or colorless spodumene can be treated to a kunzite color by?
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Irradiation followed by heating
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An intense, unstable green color can be created in spodumene by?
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Irradiation
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The color of chrome diopside is?
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Natural
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Where is a commercial source for chrome diopside?
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Russia.
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What is copal?
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Immature amber
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What amber has the highest value?
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Tranparent red amber.
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Where are ambers principal sources?
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Baltic Sea and the Dominican Republic
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What are sun spangles?
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Circular marks sometimes left in amber when treaters heat and oil it.
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What are the two basic types of coral?
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calcareous- calcium carbonate
conchiolin-protein |
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Trade in elephant ivory has been illegal since?
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1970's
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What is the most common ivory imitator?
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Celluloid
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What is ammonite?
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The fossilized remains of hard-shelled, squid-like marine mollusks that lived between 65 million and 395 million years ago.
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How old does tree resin have to be to be called amber?
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At least a million years old
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What is the most valuable red coral called?
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oxblood
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What is "engine turning"?
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Ivory shows a structure which looks like lines created on a lathe.
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What tusk produces the most valuable ivory?
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Elephant
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Paua is a Maori name for?
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Abalone shell.
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Tortoise shell is composed of?
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Protein
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Jet is an ornamental form of?
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lignite coal
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The major source of jet is?
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England
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What is moldavite?
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A natural glass
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The only source of gem-quality benitoite is?
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California
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