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365 Cards in this Set

  • Front
  • Back
  • 3rd side (hint)
Is aquamarine usually treated and why or why not?
Aquamarine is almost always heat treated to remove the yellow color component and to produce a more marketable blue color.
What is a natural glass gem?
Moldavite.
Volcanic.
What is blue sapphires most common crystal habit?
A spindel-shaped hexagonal pyramid or bipyramid.
Define 'maraba amethyst.
Less saturated in color, but uniform in color, high clarity in large crystals.
What color is Chrysoprase?
Light to medium yellowish green.
Where is the only place boulder opal is mined?
Queensland, Northeastern Australia.
Country and area.
Where is the major source of both black and white opal?
Australia.
Country only.
What are the tiny tension cracks in Moonstone called?
Centipedes.
What is moonstone a variety of?
Orthoclase feldspar.
What is the greenish blue feldspar that has gridlike white streaks and resembles turquoise called?
Amazonite.
What is Spectrolite a variety of?
Labradorite.
Define 'sun spangles'.
Circular marks sometimes left in Amber when treaters heat and oil it.
Organic stones.
Define 'tourmalinated quartz'.
A type of sagenitic quartz containing needle-like or rod-like tourmaline inclusions.
Quartz & Chalcedony.
Define 'signet'.
A table-cut gem with a flat or slightly domed top and sometimes a carved design, typically set in men's rings and cufflinks.
Quartz & Chalcedony.
What does precious opal's internal pattern look like?
Billions of uniform, submicroscopic silica spheres, stacked in an orderly pattern.
Define 'crazing'.
The network of tiny fractures that develops when an opal loses moisture.
Opal.
What kind of rock does Turquoise usually form in?
Limonite.
What are the 2 trace elements responsible for sapphires blue color?
Titanium and iron.
Where was Tanzanite discovered?
Merelani, Tanzania, Africa.
Area, country & continent.
Define 'mountain jade'.
Thick-skinned jadeite boulders.
Define 'mottling'.
An uneven distribution of color against a contrasting background.
Jade.
Define 'old mine' Jadeite.
The finest texture category of Jadeite.
Define 'new mine' Jadeite.
The coarsest texture category of Jadeite.
What is the most common color of untreated, natural Topaz?
Colorless.
Where does most gem quality rough Topaz come from?
Pegmatites.
Not country source, but growth/rock type.
What color is the finest Aquamarine?
Moderately strong, medium-dark blue to slightly greenish blue.
Define 'watermelon' tourmaline.
A tourmaline, usually elbaite, with color zoning made up of a pink central zone surrounded by a green overgrowth.
What is the most common treatment for Paraiba tourmaline?
Heat treatment.
In what Era was Jet popular in mourning jewelry?
The late Victorian Era.
Where is the most important coral-marketing center?
Italy.
What treatment for turquoise emerged in the 1980's and has treated more than 10 million carats?
The Zachery method.
Where is the major source of rough for commercial calibrated Peridot?
Arizona.
What trace element must yellow to reddish brown Topaz contain in order to attain a treated pink color?
Chromium.
Where is the major source for Imperial Topaz?
Ouro Preto, Brazil.
City & Country.
What is play-of-color called that's only seen when light travels through an Opal to the eye?
Contra Luz.
What shapes are most common in Tourmalines and why?
Slender proportioned emeral or baguette type cuts because of the elongated shape of the crystals.
What type are most gem Tourmalines?
Elbaite.
What is the most desireable play-of-color hue?
Red.
What makes 'boulder opal' more durable than other types?
It's matrix backing.
What are the 3 characteristics of Opals beauty?
Color
Pattern
Clarity
What is the rarest play-of-color?
One that contains hues across the entire spectrum.
In Opal, what is the preferred level of transparency?
It depends on the background color of the Opal.
What is done to make use of thin Opal pieces?
They are assembled into either doublets or triplets.
Where were the first black Opals discovered?
New South Wales, Lightning Ridge, Australia.
City, Mine & country.
What is Malachite's color caused by?
Copper.
Trace element.
How long ago did Opal deposits form?
15 - 30 million years ago.
What is the main composition of Opal?
Silica.
What color are the markings of sandstone matrix in Turquoise?
Tan.
Define 'Precious' Topaz.
A trade term for orange to yellow and brown Topaz.
What treatment is used to turn light-colored or colorless Spodumene into a Kunzite color?
Irradiation followed by heat treatment.
Why does Zircon need care in handling and wear?
Because of its brittleness.
What country is the world's largest supplier of Tourmaline?
Brazil.
Which type of Garnet has the widest color range?
Andradite.
Define 'Imperial Jade'.
Trade name for finest-quality, semitransparent Jadeite with even, vivid green coloration.
Define 'hololith'.
Gemstone jewelry carved entirely from a single piece of rough.
Jade.
Where is the largest supply of Opal mined?
Australia.
What percentage of the world's supply of Opal is mined in Australia?
90%.
Define 'isomorphous replacement'.
Substitution of one chemical element for another in the crystal structure of a mineral.
How many cleavage directions are found in Feldspar, Spodumene and Diopside?
2 cleavage directions.
What is adularescence caused by?
The scattering of light by stacked, alternating mineral layers.
What is the imitation for Sunstone called?
Goldstone.
Define 'hollowback'.
A cabochon with a curved, undercut bottom, designed to lighten the tone of the gem.
Garnet.
Define 'Malaya' Garnet.
Pinkish orange Garnet that is a mix of pyrope, spessartite and almandite.
Define 'Ceylon' or 'Sri Lankan' Sapphire.
Usually have a slightly grayish to strong saturation and light to medium-light tone.
Define 'Burmese' Sapphire.
Usually have a more intense color than Kashmir, sometimes more saturated as well. Also called 'Royal Blue'. Might appear inky under incandescent light.
Define 'Kasmir' Sapphire.
Violetish blue to blue, with moderately strong to vivid saturation and a medium-dark tone with a velvety luster. Also called 'Cornflower Blue'.
When was Alexandrite discovered?
1830
Define 'Spiderweb' Turquiose.
Turquiose that contains matrix in think, web-like patterns.
When were the first synthetic flame fusion star Rubies made?
1940's
Give a decade.
How old must resin be to be called Amber?
At least 1 million years old.
Where is the main polishing center for Jadeite?
China.
Country.
What are the 9 colors that Jadeite can be?
Green
Lavender
Red
Orange
Yellow
Brown
White
Black
Gray
What is the most valueable transparency of Jadeite?
Semitransparent.
What source emerged in the 1990's as a significant source of good to fine quality blue Sapphire?
Madagascar.
What location supplies blue Sapphires that are most likely not treated?
Yogo Gulch, Montana.
Mine and state.
When was Kashmir's most significant production period for blue Sapphire?
1881-1887
Define 'Padparascha'.
Lotus flower; intensely saturated, light to medium pinkish orange to orange-pink Sapphire.
Define 'Chilean' Lapis Lazuli.
Often tinged or spotted with green, with obvious calcite matrix.
Define 'Russian' or 'Siberian' Lapis Lazuli.
Various tones and intensities of blue. Contains pyrite and might contain some calcite.
What is a major source of Cats-eye Chrysoberyl?
Sri Lanka.
Country.
What is play-of-color?
The interaction of light with Opal's internal structure of stacked silica spheres.
What is the most expensive Opal?
Black Opal (Lightning Ridge).
Which Opal makes up the bulk of commercial-quality on the market?
White Opal.
What is the transparency range of white Opal?
Translucent to opaque.
Where was Jadeita first fashioned and used as an ornamental object?
China.
Country.
What element causes Jadeite's green color?
Chromium.
What are the largest and 2nd largest Ruby exporters?
Thailand is first with 61% of its exports shipping to the USA. India is the second largest exporter.
Define 'Geuda'.
Milky, grayish or brownish corundum that can be heat treated to a fine blue color.
Sapphire.
What 2 countries produce the finest Peridot?
Myanmar & Pakistan.
Where is a major source of Nephrite?
New Zealand.
Metamict zircons are also known as what?
Low Zircons.
What method is used to produce synthetic Aquamarine?
Hydrothermal.
Where is the major source of Turquoise today?
Southwestern US.
Region.
What is the most valued color of Emerald?
Bluish green to green with strong to vivid saturation and medium to medium dark tone.
What color range is the most valueable Fire Opal in?
Uniform red-orange (R/O) to bright red (R).
What colors do color-change Sapphires typically change from and to?
From violetish blue to reddish purple.
Which country is the largest producer of Chrome Tourmaline?
Tanzania.
Define 'sagenitic' Quartz.
Transparent quartz, usually rock crystal, that contains eye-visible inclusions, often named according to the type of inclusions it contains.
Define 'parti-colored'.
Gems that show color zoning with 2 or more colors.
What trace element causes Paraiba Tourmaline's colors?
Copper.
Which era did Moonstone go out of style in?
Art Deco Era, 1920's.
What color is the adularescence in the finest Moonstone?
Blue.
Define 'Rubellite'.
Trade name for pink to red elbaite Tourmaline.
Define 'Pailin' or 'Cambodian' Sapphire.
Generally violetish blue to very slightly greenish blue with medium to dark tone.
How do most gem Tourmalines form?
In pegmatites.
Define 'Paraiba' Tourmaline.
Trade term for rare, expensive, vibrant green to blue violet elbaite tourmalone, originally found only in Brazil's Paraiba state.
Define 'Egyptian' Turquoise.
Greenish blue to yellowish green.
Define the trade term 'Zambian' Emerald.
They are slightly darker and more bluish than Columbian Emeralds, often with higher clarity.
Define 'Brazilian' Emerald.
Describes Emeralds that are lighter in tone than other Emeralds.
Where is the only commerical source for Charoite?
Russia.
What are the 3 elements that cause the color in most fancy Sapphire?
Iron
Titanium
Chromium
What are the 2 main sources for Amber?
Baltic Sea
Dominican Republic
What are Ruby's pleochroic colors?
Red to purplish red in one direction; orangy red in another.
How should a cutter fashion a Ruby to bring out its most appealing pleochroic color?
Orient the table facet perpendicular to the long crystal direction.
What colors of Topaz are the rarest and most valueable?
Red & pink; including Imperial Topaz.
Where does Peridot sit on the Mohs Scale?
6.5 - 7
What types of jewelry is Peridot best used in?
Pins, pendants & earrings.
What are the 2 most important Tourmaline treatments?
Heating
Irradiation
What are the main 4 reason Paraiba Tourmaline commands high prices?
Attractiveness
Highly saturated hues
Extremely low supply
Strong demand
What is semi-black Opal's background color?
Grayish.
Where is the most important source of Rhodolite in recent years?
East Africa.
Where is the major source of Jet?
England.
Define 'Imperial' Topaz.
A widely used trade term for gem quality Topaz of medium reddish orange to orange-red color.
Where is the world's only source of Bixbite?
Wah-wah mountains, Utah.
Mine & location.
What trace element causes the red color of Bixbite?
Manganese.
Is Morganite treated and why or why not?
Morganite is almost always treated to produce or improve the pink color.
What is the most common number of rays in a star corundum?
Six.
Where are Brazilian Emeralds mined from?
From pegmatites, where they intersect with schists.
Not locale, but rock type.
Where is the major source of the world's large, fine color Peridot?
Myanmar.
Where is the most important source of Rhodolite in recent years?
East Africa.
What element causes pink corundum?
Manganese.
Where is the major source of Jet?
England.
Define 'Imperial' Topaz.
A widely used trade term for gem quality Topaz of medium reddish orange to orange-red color.
Where is the world's only source of Bixbite?
Wah-wah mountains, Utah.
Mine & location.
What trace element causes the red color of Bixbite?
Manganese.
Is Morganite treated and why or why not?
Morganite is almost always treated to produce or improve the pink color.
What is the most common number of rays in a star corundum?
Six.
Where are Brazilian Emeralds mined from?
From pegmatites, where they intersect with schists.
Not locale, but rock type.
Where is the major source of the world's large, fine color Peridot?
Myanmar.
What element causes pink corundum?
Manganese.
Where is the most important source of Rhodolite in recent years?
East Africa.
Where is the major source of Jet?
England.
Define 'Imperial' Topaz.
A widely used trade term for gem quality Topaz of medium reddish orange to orange-red color.
Where is the world's only source of Bixbite?
Wah-wah mountains, Utah.
Mine & location.
What trace element causes the red color of Bixbite?
Manganese.
Is Morganite treated and why or why not?
Morganite is almost always treated to produce or improve the pink color.
What is the most common number of rays in a star corundum?
Six.
Where are Brazilian Emeralds mined from?
From pegmatites, where they intersect with schists.
Not locale, but rock type.
Where is the major source of the world's large, fine color Peridot?
Myanmar.
What element causes pink corundum?
Manganese.
What is the name of Columbia's 3 most famous Emerald mines?
Coscuez
La Pita
Muzo
What is the most common Sapphire synthesis method?
Flame fusion.
What do experts think Fire Opal's background color is caused by?
Iron impurities.
What is the hue range for Ruby?
Orangy red (OR) to purplish red (PR).
What is the top color range for Ruby?
Red (R) to slightly purplish red (slpR)
What is the highest saturation and preferred tone for Ruby?
Vivid & medium to medium dark.
What is 'Polar Jade'.
High quality nephrite.
Define 'reconstructed' Turquoise.
A Turquoise imitation made of a mixture of powdered minerals, dyed and bonded with plastic or epoxy resin.
Where is the world's major souce of Lapis Lazuli?
Afganistan.
Define 'Burmese' Ruby.
The finest hue, tone and saturation. Also called 'Pigeon Blood'.
Define 'Thai' Ruby.
Brownish red, purplish red, medium to very dark tone, no fluorescence, black extinction areas. Also called 'Mud Rubies'.
Define 'Ceylon' Ruby.
Purplish red, pinkish red, medium to very light tone, brighter. Also known as 'Pink Sapphire'.
What are the 2 types of Coral? Give an example of each.
Calcareous... Pink
Conchiolin... Golden
What is immature Amber called?
Copal.
What color of Amber is the most valueable?
Red.
What is the color change in Alexandrite caused by?
Chromium.
What is the most valueable color of Coral called?
Oxblood Red.
Define 'River Jade'.
Weathered, thin-skinned Jadeita boulders.
What color might Jadeite turn if it is heat treated?
Orange and reddish colors.
What is the finest quality Jadeite called?
Imperial Jade.
Where were the first black Opals discovered?
New South Wales, Lightning Ridge, Australia.
City, Mine & Country
What is done to make use of thin Opal pieces?
They are assembled into either doublets or triplets.
In Opal, what is the preferred level of transparency?
It depends on the background color of the Opal.
What is the transparency range of white Opal?
Translucent to opaque.
Which Opal makes up the bulk of commercial quality on the market?
White Opal.
Define 'mottling'.
An uneven distribution of color against a contrasting background.
What color is Chrysoprase?
Light to medium yellowish green.
What color are the markings of sandstone matrix in Turquoise?
Tan.
Define 'precious' Topaz.
A trade term for orange to yellow and brown Topaz.
What treatment is used to turn light colored or colorless Spodumene into a Kunzite color?
Irradiation followed by heat treatment.
Define 'watermelon' Tourmaline.
A Tourmaline, usually elbaite, with color zoning made up of a pink central zone surrounded by a green overgrowth.
When was Jet popular in mourning jewelry?
Late Victorian era.
What is the most common color of untreated, natural Topaz?
Colorless.
What does Precious Opal's interal pattern look like?
Billions of uniform, submicroscopic silica spheres, stacked in an orderly pattern.
What kind of rock does Turquoise usually form in?
Limonite.
Define 'Chilean' Lapis Lazuli.
Often tinged or spotted with green, with obvious calcite matrix.
What is blue Sapphire's most common crystal habit?
A spindel-shaped hexagonal pyramid or bipyramid.
Where does most gem quality rough Topaz come from?
Pegmatites.
How does it grow, rock type.
What type are most gem Tourmalines?
Elbaite.
What color is the finest Aquamarine?
Moderately strong, medium-dark blue to slightly greenish blue.
What is adularescence caused by?
The scattering of light by stacked, alternating mineral layers.
What is Malachite's color caused by?
Copper.
Where is the only place Boulder Opal is mined?
Queensland, northeastern Australia.
Area & country.
What treatment for Turquoise emerged in the 1980's and has treated more than 10 million carats?
The Zachery Method.
Define 'Tourmalinated' Quartz.
A type of sagenitic Quartz containing needle-like or rod-like Tourmaline inclusions.
What is a natural glass gem?
Moldavite.
How long ago did Opal deposits form?
15 - 30 million years ago.
What is the main composition of Opal deposits?
Silica.
Define 'crazing'.
The network of tiny fractures that develops when an Opal loses moisture.
Define 'Sun Spangles'.
Circular marks sometimes left in Amber when treaters heat and oil it.
Organics.
What is Spectrolite a variety of?
Labradorite.
What is play-of-color?
The interaction of light with Opal's internal structure of stacked silica spheres.
What is the most expensive Opal?
Black Opal from Lightning Ridge.
Define 'signet'.
A table cut gem with a flat or slightly domed top and sometimes a carved design, typically set in men's rings and cufflinks.
Define 'Maraba' Amethyst.
Less saturated in color, but uniform in color, high clarity in large crystals.
What are the tiny tension cracks in Moonstone called?
Centipedes.
Where is the most important Coral marketing center?
Italy.
Where was Tanzanite discovered?
Merelani, Tanzania, Africa.
Area, Country & Continent.
What are the 2 trace elements responsible for Sapphire's blue color?
Iron and titanium.
Why does Zircon need care in handling and wear?
Because of its brittleness.
What country is the world's largest supplier of Tourmaline?
Brazil.
What is Rhodolite a mixture of?
Pyrope and Almandite.
What type of Garnet are both Tsavorite and Hessonite varieties of?
Grossularite.
What is Chalcedony with curved or angular bands or layers that differ in color and transparency called?
Agate.
What element colors Tsavorite?
Vanadium.
What is the smallest crystal size in gemology?
Cryptocrystalline.
What does the trade term 'Black Onyx' refer to?
Treated black Chalcedony.
Where was the major source of Amethyst in the 19th century found?
Zambia.
How is dark Amethyst lightened?
Heat treatment.
Where is the major source for commercial Amethyst?
Brazil.
Where is the source for natural Ametrine?
Eastern Bolivia.
What is Amethyst's most prized color?
Medium-dark strong reddish purple.
What is crystalline Quartz known as?
Chalcedony.
Where does the majority of Citrine in the market come from?
Heating Amethyst.
What are the 3 patterns of play-of-color on Opal?
Pinfire
Flash
Harlequin
Which pattern on Opal is the most desireable?
Harlequin.
Define 'Type B' Jadeite.
Natural Jadeite that's bleached in acid to remove undesireable staining, then impregnated with wax or polymers.
What is the first step in evaluating an Opal?
Determining its type.
Where is the major source for top color Turquoise today?
China.
What is the finest color of Turquoise?
Intense medium blue.
When was Ivory trading made illegal?
Mid 1970's.
Define 'Dhun'.
Smoky corundum that turns blue when heat treated.
Sapphire.
What are blue Sapphires pleochroic colors?
Slightly greenish blue and slightly violetish blue.
Are Tourmalines a group or a variety?
Tourmalines are a group of minerals that share the same crystal structure but have slightly different chemical and physical properties.
Where do most fine Sapphires over 100 carats come from?
Sri Lanka.
What country is the world's largest blue Sapphire exporter?
Thailand.
Define 'potch' Opal.
Opal that lacks play-of-color.
Define 'matrix'.
A gem material's host rock, which sometimes becomes part of the finished gem.
Define 'boulder' Opal.
Thin layers of Opal, cut to include matrix.
Define 'Kanchanaburi' Saphhire.
Blue to slightly greenish blue with light to dark tone. Less saturated stones have a grayish appearance. Most have minute inclusions that give a milky appearance.
Why do cutters have to pay careful attention to Tourmaline's cut?
Because Tourmaline has strong pleochroism.
How are extremely valueable Opal cut?
To best display their play-of-color.
What treatment can create a golden color from black Coral?
Bleaching.
What easily distinguishes colorless Zircon from Diamond and synthetic Cubic Zirconia?
Its strong double refraction.
What country is the largest Ruby importer?
The US.
Name 6 main importers of Ruby other than the US.
Germany, Italy, Taiwan, China, Korea & Hong Kong.
Other than the US.
What country is the 2nd largest importer of Rubies, price wise?
Switzerland.
What is a major source of black star corundum?
Australia.
Which organic shows a structure called 'engine turning' which looks like lines created on a lathe?
Ivory.
What is the most prized chatoyant gem in the world?
Cats-eye Chrysoberyl.
What do all Garnets share?
Crystal structure.
Where is Spessartite usually found?
Pegmatites.
Rock growth.
How much (%) water does most Opal contain?
3 - 10 percent.
Define 'Slocum Stone'.
An Opal imitation made of glass that appeared in the late 1970's.
What color is Hiddenite?
Vivid medium green.
Define 'Thai' Sapphire.
Violetish blue to slightly greenish blue with medium-dark to dark tone. Also described as inky blue or blue-black.
Define 'Type A' Jadeite.
Natural Jadeite enhanced only with a surface coating of wax.
What element causes the purest blue colors of Turquoise?
Copper.
What are the 7 typical characteristic inclusions in Ruby?
Silk (Rutile needles), boehmite needles, included crystals, fingerprints, growth zoning, color zoning & color banding.
What is the only Ruby clarity characteristic that has a positive effect?
Silk.
Where is the recent source that is the leading producer of small, commercial quality Aquamarine?
China.
Where is the most important Aquamarine source?
Brazil.
What is Jet an ornamental form of?
Lignite coal.
What is responsible for the color of Amethyst?
Color centers caused by natural irradiation acting on trace elements of iron in its crystal structure.
What are the 5 main Ruby treatments?
Heat treating, fracture & cavity filling, dyeing, quench-crackling & lattice diffusion.
What is the only accepted form of treatment for Ruby?
Heat treatment.
Who created the first marketable synthetic Opal?
John Slocum.
What trace element colors Peridot?
Iron.
What type of Opal dominates the US market?
Commercial quality white Opal.
What are the 2 methods used to grow synthetic Emeralds?
Flux & hydrothermal.
How are commercial grade white and assembled Opal cut?
Into standard, calibrated sizes.
Define 'Agate'.
Chalcedony with curved or angular bands or layers that differ in color and transparency.
What treatment is used to make Zircon blue?
Heat treament.
What is the best way to evaluate Opal?
By keeping conditions, methods & samples consistant.
When was Brazil's deposit of Alexandrite discovered?
1980
Define 'stabilized' Turquoise.
A trade term for polymer impregnated Turquoise.
Do Sapphires from basaltic rock have higher or lower iron content?
Higher iron content.
What is the type of matrix found as a layer in finished boulder Opal?
Ironstone.
What are the 3 cuts most widely used for Topaz and why?
Elongated ovals, pears & emerald cuts because Topaz crystals are elongated.
What are the 4 main emerald sources?
Columbia
Brazil
Zambia
Zimbabwe
Define 'relatively old mine' Jadeite.
The medium texture category of Jadeite.
What is the most convincing Tanzanite simulant?
Synthetic Forsterite.
Where is the major source of Fire Opal?
Mexico.
Which element increases the amount of blue in an Emerald's color?
Iron.
What is Tanzanite's best color?
Strongly saturated blue or violetish blue.
What causes the chatoyancy in Cats-eye Quartz?
Multiple slender crystals.
Define 'Type C' Jadeite.
Natural Jadeite that has been dyed and often bleached and impregnated with wax or polymers.
What city is the center of the Jadeite mining district in Myanmar?
Hpakan.
What size of crystals make up Tiger's Eye?
Microcrystalline.
What causes the asterism in black star Sapphire?
Hematite.
What is the highest transparency star Sapphire should have for best quality?
Semi-transparent.
How do cutters orient the table to emphasize the most desireable color in Emeralds?
So the table is perpendicular to the crystal growth.
What is the term 'spinach' Jade used to describe?
Nephrite's green color.
What is the best way to clean Peridot and why?
In warm soapy water because it is sensitive to rapid temperature changes and chemicals.
Define 'Paua'.
The Maori name for abalone shell.
Organics.
What is the imitation for Sunstone called?
Goldstone.
Which type of Garnet has the widest color range?
Andradite.
Define 'hololith'.
Gemstone jewelry carved entirely from a single piece of rough.
Where is the largest supply of Opal mined?
Australia.
What percentage of the world's Opal supply is in Australia?
90%
Where is the major source of rough for commercial calibrated Peridot?
Arizona.
What trace element must yellow to reddish brown Topaz contain in order to attain a treated pink color?
Chromium.
What country is the major source of Imperial Topaz?
Ouro Preto, Brazil.
Mine & Country.
What is play-of-color called that is only seen when light travels through an Opal to the eye?
Contra Luz.
What shapes are most common in Tourmalines and why?
Slender proportioned emerald or baguette type cuts because of the elongated shape of the crystals.
What is the most desireable play-of-color hue?
Red.
What makes 'boulder' Opal more durable than other types of Opal?
The matrix backing.
What are the 3 characteristics of Opal's beauty?
Color
Pattern
Clarity
What is the rarest play-of-color?
Contains hues across the entire spectrum.
What are the 3 imitations used for Lapis?
Glass
Plastic
Ceramic
What are the 3 treatments used for Lapis?
Dyed
Wax or polymer impregnated
Heated then dyed
Define 'Persian Blue' Turquoise.
Robin's egg blue.
Color name.
Define 'Chrome' Tourmaline.
Trade term for a vibrant green Tourmaline that is colored by traces of vanadium, chrome, or both.
What is Rainbow Moonstone a trade name for?
Labradorite.
What are the 3 basic chemical elements all Feldspars have in common?
Silicon
Aluminum
Oxygen
What are the 5 processes for creating synthetic Sapphire?
Flame fusion
Flux
Pulling
Floating Zone
Hydrothermal
What are the 7 types of Opal?
Black
White
Crystal
Water
Boulder
Fire
Assembled
What color range does the highest valued Sapphire fall into?
Blue to violetish blue.
Define 'Tanavyte'.
Trade name for purple synthetic YAG as a Tanzanite simulant.
What are the 3 imitations used for Lapis?
Glass
Plastic
Ceramic
What are the 3 treatments used for Lapis?
Dyed
Wax or polymer impregnated
Heated then dyed
Define 'Persian Blue' Turquoise.
Robin's egg blue.
Color name.
Define 'Chrome' Tourmaline.
Trade term for a vibrant green Tourmaline that is colored by traces of vanadium, chrome, or both.
What is Rainbow Moonstone a trade name for?
Labradorite.
What are the 3 basic chemical elements all Feldspars have in common?
Silicon
Aluminum
Oxygen
What are the 5 processes for creating synthetic Sapphire?
Flame fusion
Flux
Pulling
Floating Zone
Hydrothermal
What are the 7 types of Opal?
Black
White
Crystal
Water
Boulder
Fire
Assembled
What color range does the highest valued Sapphire fall into?
Blue to violetish blue.
Define 'Tanavyte'.
Trade name for purple synthetic YAG as a Tanzanite simulant.
What is Iolite's most valueable face-up color?
Blue.
What are the 2 causes of color in most Topaz?
Color centers & chromium.
What treatments are used to create blue Topaz?
Radiation & heat treament.
Why do cutters pay extra attention to cutting, polishing, mounting & wear of Topaz.
Because of Topaz's basal cleavage.
Rubellite Tourmaline is colored by what trace element?
Manganese.
What treatment lightens many green and blue Tourmalines?
Heat treatment.
What is the estimated percentage of fracture filled emeralds?
90% or more.
What 2 countries account for 75% of Emerald purchases worldwide?
US
Japan
What 2 elements color rare natural blue Spinel?
Cobalt & iron.
What are the 3 elements that are responsible for Emerald's color?
Chromium
Vanadium
Iron
Define 'background color'.
An Opal's bodycolor, independent of its play-of-color.
Opal.
Plastic imitation Opal was first marketed in the late 1980's in what country?
Japan.
Define 'show points'.
Spots of color near the surface of a Jadeite boulder, where the skin is thin enough to allow color to show through.
Jadeite.
What element colors red Spinel?
Chromium.
How are Zambian Emerald crystals usually shaped?
Irregularly.
Who produced a hydrothermal synthetic Emerald layer over faceted Beryl seeds in the 1960's?
Johann Lechleitner.
What is the treatment called that involves immersing Opal in concentrated sulfuric acid?
Sugar treatment.
What is the most common Emerald simulant?
Synthetic Spinel triplets.
When was the Sandawana mine discovered?
1950's
Emerald.
When were Emeralds discovered in Zambia?
1930's
Define 'Persian' or 'Afghan' Lapis Lazuli.
Intense, uniform, medium-dark, slightly violetish blue. Contains little or no pyrite and no calcite.
Where is a main source for Chrome Diopside?
Russia.
What treatment is used to create an intense, unstable green color in Spodumene?
Irradiation.
What element causes Sapphire's color change?
Vanadium.
What is tortoise shell composed of?
Protein.
What is the toughness of Jadeite on an exceptional to fair scale?
Exceptional.
What color of Jadeite is currently sourced from Guatemala?
Black.
Define 'American' or 'Mexican' Turquoise?
Light blue, greenish blue to bluish green.
Where were Trapiche Emeralds first discovered?
Muzo, Columbia.
Mine & Country.
What are the 2 most popular Sapphire simulants?
Glass
Synthetic Spinel & flame fusion Sapphire doublets.
Define 'Australian' Sapphire.
Violetish blue to very strongly greenish blue with medium-dark to very dark tone. Often show strong greenish blue Pleochroism. Also called inky blue.
Define 'botryoidal'.
A crystal growth habit with a bumpy appearance similar to a bunch of grapes.
Quartz & Chalcedony
Define 'Indicolite'.
Trade term for blue Tourmaline.
Define 'metamict'.
A mineral that has been broken down from a crystalline to a partly amorphous state by emanations from radioactive impurities.
What is the transparency of gray-base black Opal?
Opaque.
What produces Lapis Lazuli's prized royal blue color?
Lazurite.