Colored Stones-Part 2

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

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