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