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748 Cards in this Set

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Velvety blue to violetish blue, in medium to medium-dark tones, with strong to vivid saturation.
fine sapphire
What trace elements cause the blue of sapphire?
iron and titanium
A smoky corundum that turns blue when treated is called _______ .
Dhun
True or false:
Higher levels of iron make basalt-hosted sapphires darker than non-basaltic sapphires.
true
What is the trade name considered as the finest blue sapphire?
"Kashmir"
Is color zoning a common sapphire characteristic?
Yes
True or False:
Most sapphires are heat treated to improve their appearance.
True
True or False:
Fine quality, untreated sapphires make up a small but extremely valuable segment of the sapphire market.
True
What country buys about half of the blue sapphires on the world market?
USA
Kashmir sapphires owe their reputation to a brief period of output during what time period?
1880's
What country is a major center of the corundum trade, funneling a steady flow of gems from worldwide sources into the consumer market?
Thailand
What country is the world's largest source of dark blue, commercial quality blue sapphires?
Australia
What country has become a significant source of good to fine quality blue sapphires?
Madagascar
What is the most common sapphire synthesis method?
Flame fusion
A milky, grayish, or brownish corundum that can be treated to a fine blue color is called ________ .
Geuda
Blue to violetish blue.
Fine blue sapphire
What trace elements cause blue sapphire's color?
titanium and iron.
Blue sapphires that originate in basaltic rock generally have a _________ .
higher iron content.
Finer quality Kashmir blue sapphires typically show what type of appearance?
Velvety
Type of sapphire described as inky.
Australia
Blue sapphire's most common crystal habit is _________.
spindle-shaped hexagonal pyramid or bipyramid.
Most fine sapphires of 100 cts. come from what country?
Sri Lanka
What country emerged in the 1990's as a significant source of good to fine quality sapphire?
Madagascar
What country is the world's largest blue sapphire EXPORTER ?
Thailand
The sapphire market level supplied by Switzerland is ________ .
upper.
Kashmir's most important sapphire production period was from ________ to ________ .
1881 to 1887.
When did Madagascar become a significant source of blue sapphire?
1990's
What location supplies sapphires that are most likely not heat-treated?
Yogo Gulch
A "Kashmir" sapphire's blue is also known as _______ .
Cornflower blue.
A "Burmese" sapphire's blue is known as ______ blue and is considered somewhat _______ .
Royal ; inky
The "Ceylon" or "Sri Lanka" sapphire's saturation is _______ and ________ . The tone is _________ to _________ .
grayish and strong saturation

light to medium light tone.
The "Palin" or "Cambodian" sapphires are typically ______ to _______ in color and look best when fashioned into smaller sizes.
violetish blue to slightly greenish blue
The "Kanchanaburi" sapphires are less saturated and are generally _______ to _______ in color with a ______ to _________ tone. Minute inclusions cause it to have a grayish appearance.
blue to greenish blue color
light to dark tone

similar to Sri Lankan but, not as brilliant
"Thai" sapphires are ________ to _________ in color and often described as _________ or _________ .
violetish blue to slightly greenish blue

inky blue or blue-black
"Australian" sapphires often show _____________ plechroism.
strong greenish blue
Lapis Lazuli is valued for its ___________ and rich ________ color.
history ; blue
What produces lapis lazuli's prized royal blue color?
lazurite
Lapis Lazuli's value is based on color and the presence or absence of _________ or _________ .
calcite or pyrite
What 3 treatments are used with lapis?
dyed
impregnanted with wax or plastic
heated and then dyed
What country is the major source for lapis lazuli?
Afghanistan
What materials have been used as lapis immitations?
Glass, plastic and ceramic
People value turquoise for it's combination of what two traits?
ancient heritage and attractive color
Turquoise is judged by what three factors?
color
texture
matrix
What is the most prized color of turquoise?
intense / uniform /medium blue
What element causes turquoise to appear greenish blue?
Iron
What element causes turquoise to have a pure blue color?
Copper
What location is the world's largest producer of turquoise?
Southwestern US
What country is the major source for top color turquoise?
China (Hubai Province)
What is the most common turquoise immitation?
Plastic
The finest grade of lapis lazuli is called ________ .
"Afghan"
The lapis lazuli trade grade that's often spotted with green and shows obvious calcite is called ________ .
"Chilean"
The finest color of turquoise is ______________ .
Intense medium blue
The purest blue colors of turquoise are caused by _________ .
copper
What is the trade term for top-color turquoise?
Persian
Turquoise usually forms in __________ .
Limonite
What is the color of the markings that sandstone matrix creates in turquoise?
tan
Stabalized turquoise is a tade term for what?
Polymer-impregnated turquoise
A new turquoise treatment that appeared in the 1980's and has been used to treat more thabn 10 million carats is _____________ .
Zachary method
The major source of turquoise today is ___________ .
Southwestern US.
Reconstructed turquoise is __________ .
Immitation
Malachite's color is caused by what element?
Copper
The only commercial source of charolite is in what country/
Russia
Chalcedony with curved or irregular bands or layers that differ in color and transparency.
Agate
A crystal growth habit with a bumpy appearance similar to a bunch of grapes.
Botryodal
A cryptocrystalline quartz aggregate.
Chalcedony
A property of some crystals that causes them to vibrate at a constant frequency when subjected to an electrical current.
Piezoelectricity
A type of sagenitic quartz containing needle-like rutile inclusions.
Rutilated quartz
A transparent quartz, usually rock crystal, that contains eye-visable inclusions, often named according to the type of inclusions it contains.
Sagenitic
A table-cut gem with a flat or slightly domed top and sometimes a carved design, typically set in men's rings and cufflinks.
Signet
A type of sagenitic quartz containing needle-like or rod-like tourmaline inclusions.
Tourmalated quartz
Cryptocrystalline quartz is known as ___________ .
Chalcedony
Chalcedony with curved or irregular bands or layers that differ in color and transparency is known as ________ .
Agate
What type of crystalline has the smallest crystal size?
Cryptocrystalline
In the nineteenth century, a major source of amethyst was discovered in what country?
Brazil
The color of amethyst results from __________________ .
Color centers acting on iron .
One of amethyst's finest colors is _____________________ .
medium-dark strong reddish purple.
What country is the major source for commercial-quality amethyst?
Brazil
"Maraba" amethyst is often
Uniform in color
What treatment lightens dark amethyst?
heat
How is most of the citrine on the market produced?
By heating amethyst
What country is the source for natural ametrine?
Bolivia
What type of aggregate is tiger's eye quartz?
microcrystalline
Multiple slender crystals or channels cause this in cat's-eye chacelony.
Chatoyancy
What is the color of chrysoprase?
Yellowish green
Treated black chalcedony is also known by the trade term ____________ .
Black onyx
The trade considers what gemstone to have the finest green among the colored stones?
Emerald
When all factors are equal, a great difference in emerald value can be caused by slight differences in __________, ____________ and ____________ .
hue, tone and saturation.
Emerald's color-causing trace elements are _________ , __________ and ___________ .
Chromium
Vanadium
Iron
What can cause a great reduction in a finished emerald's value?
Poor cutting
The trade accepts the fact that most emeralds contain _____________ .
Eye visable inclusions
Inclusions that make an emerald less valuable also make it less _____________ .
Transparent.
How are emerald's fractures usually filled?
Oil
Resin
Both.
What type of emerald commands premium prices?
Untreated
What is the safest way to clean emeralds?
Gentle scrubbing with warm soapy water.
What two countries account for 75% of emerald purchases worldwide?
The US and Japan.
What four countries provide most of the world's emeralds?
Brazil
Columbia
Zambia
Zimbabwe
The world's emeralds are judged by what country's finest?
Columbia
What country's emerald mines have fewer fractures than emeralds from other sources?
Africa
What is the most common emerald imitation used in jewelry?
Synthetic spinel triplets
What two methods are used to synthesize emeralds?
Flux and hydrothermal
Bluish-green to green.
Finest Emerald
What element increases the amount of blue in an emerald's color?
Iron
The trade term "Zambian" describes emeralds with ________________ and ______________ than Columbian.
More bluish color and darker tone
What type source rock are Brazilian emeralds mined from?
Pegmatites, where they intersect with schists.
To emphasize the most desirable color, cutters orient a fashioned emerald with it's table _____________ .
Perpendicular to the crystal length
What is the estimated percentage of fashioned emeralds that contain filled fractures?
90% or more
What to countries account for about 75% of emerald purchases worldwide?
US and Japan
Four major emerald sources are Columbia, Zambia, Brazil and _____________ .
Zimbabwe
One of Columbia's traditional emerald mines is called ____________ .
Coscuez
Compared to emerald's from other sources, emeralds from African mines generally contain ____________ .
Fewer fractures.
Emerald is a variety of what species?
Beryl
What coloring of the stone disqualifies it from being considered and emerald.
Too yellowish or too bluish
Name the two most common clarity characteristics in an emerald.
Fractures and liquid inclusions
What does the trade term "jardin" mean?
"jardin" - French word for garden. A descriptive term for an emerald's inclusions that look mossy or garden-like.
Natural emerald with colorless or colored filling.
Level 1 Treatment
Natural emerald having filling that is minor, moderate or significant.
Level 2 Treatment
Type of filler (upon request) if the laboratory is equipped.
Type 3
Does the GIA provide Level 3 emerald treatment identification?
No.
What is the name for an emerald in which it's inclusions form a star-like pattern of rays.
Trapiche
What are the three signs that point to an "emerald" being a glass immitation?
Gas bubbles
Concave surfaces
Rounded facet junctions
Reddish orange to orange red.
Imperial topaz
The most valuable topaz varieties are _____________ .
Pink
Red
Most gem-quality topaz comes from what growth source?
Pegmatites.
The term precious topaz is used for ___________ .
Yellow to orange stones.
What is the most common color of untreated, natural topaz?
Colorless.
Wah Wah mountain area.
Imperial topaz source
In order to obtain a treated pink color, yellow to reddish brown topaz must contain elemant
Chromium
Medium dark blue to slightly greenish blue.
Finest Aquamarine
Which method is used to produce synthetic aquamarine?
Hydrothermal
The most important source country for aquamarine is ____________ .
Brazil
Which recent source is the leading producer of small, commercial-quality aquamarine?
China
Most aquamarine has it's color improved by what treatment?
Heat
What color is morganite beryl?
Pink
What gemstone is the rarest beryl?
Red beryl
What color is morganite beryl?
pink
The only source of red beryl is located in what US state?
Utah
What causes the wide variety of colors in topaz?
Color centers and chromium.
Why does topaz require special care and handling?
Cleavage.
What area in Brazil is the world's major commercial source of imperial and red topaz.
Ouro Preto
Which treatments are involved with topaz?
Heating
Heating and irradiation
What are the two most important considerations for buyers of treated blue topaz?
Price and uniformity
The finest most saturated color of aquamarine is normally shown in ____________ .
Large sizes.
What three countries are the leading producers of aquamarine?
Brazil
Pakistan
China
What trace element causes red beryls color?
Manganese
What distinguishes green beryl from emerald?
Tone and saturation
Because of topaz's elongation, how are they cut?
long ovals
pears
emerald
What is the trade term for a highly prized, vivid blue adularescence displayed for the finest moonstone?
Blue sheen
Tiny tension cracks in moonstone that iterfere with adularescence and reduce value are called _______ .
Centipedes
What is the trade term for an imitation of aventurine feldspar made of glass that contains copper crystals?
Goldstone
Why does feldspar, spodumene and diopside have weak consumer recognition?
Because of unpredictable supplies
What are the most widespread minerals on earth?
Feldspars
How many cleavage directions are found in feldspar, spodumene and diopside?
Two
What three basic chemical elements do all feldspars contain?
aluminum
oxygen
silicon
Moonstone is a variety of ________ .
Orthoclase
In which era did moonstone go out of style?
Art Deco
What color is the finest adularescence of the finest moonstone?
Blue
Tiny tension cracks in moonstone are called what?
Centipedes
Rainbow moonstone is a trade term for a type of ________ .
Labradorite
Spectrolite is a variety of _________ .
Labrodorite
The greenish blue feldspar that has gridlike white streaks and resembles turquoise is called __________ .
Amazonite
Medium green.
Hiddenite
The scattering of light by stacked, alternating mineral layers?
Moonstone's adularescence
What selling point is used for sunstone from Oregon?
It isn't treated
The high clarity and lack of treatment make what stone an attractive emerald alternative?
Chrome diopside.
What causes sunstone's redish or golden sheen?
small inclusions
What causes sunstone's glittering reflections?
larger inclusions
Intense pink and intense violetish purple.
Kunzite
colorless
semi-transparent to nearly transparent
vivid blue adularescence
Finest moonstone
Opal is composed of primarily of __________ .
Silica
When did most opal form?
15 to 30 million years ago.
What is the percentage of water that most opal contains?
3 to 10 percent
What is semi-black opal's background color?
grayish
What is the transparency of gray-based black opal?
opaque
What is the transparency range of white opal?
translucent to opaque
The type of matrix found as a layer in finished boulder opal is comprised of __________ .
ironstone
Experts think fire opal's background color is caused by _________ .
Iron impurities
In opal, a pattern of large distinct, usually rectangular patches of play-of-color with edges that touch each other is called __________ .
Harlequin
Play-of-color that's seen only when light travels through an opal to the eye is called _________ .
Contra luz
Where were the first black opals discovered?
New South Wales, Australia
What is the first step in evaluating an opal?
Determine its type
Which treatment involves immersing opal in concentrated sulfuric acid?
sugar
Who created the first marketable synthetic opal>
Pierre Gilson
Plastic imitation opal was first marketed in the late 1980's in what country?
Japan
What is precious opal made of?
Billions of uniform, submicroscopic silica spheres, stacked in an orderly pattern.
What type of opal commands the highest prices?
black
What type of opal makes up the bulk of commercial-quality on the market?
white
What makes boulder opal the most durable?
the matrix backing
Uniform red-orange to bright red color
Finest fire opal
What is one of the few opal types that is cut into a faceted gem?
fire opal
What three things combine to create and opal's unique beauty?
Color
Pattern
Clarity
How are opals divided into types?
by background color
What is the rarest play-of-color?
Displays hues across the entire spectrum.
What is considered the most valuable play-of-color hue?
red
In general what is the most preferred play-of-color pattern?
large, closely arranged color patches.
What percentage of the world's total opal supply comes from Australia?
90%
What country is the major source for fire opal?
Mexico
Commercial-quality white opal dominates what country's market?
the US
What three things should be kept consistant when evaluating opal?
conditions
methods
samples
In opal, very small patches or "dots" of play-of-color is known as _________ .
pPinfire
Large areas of play-of-color is called _______ .
Flash
An opal with a gray background that appears opaque is known as a __________ .
Semi-black opal
An opal with a dark background that is tranparent to semi-transparent and is valued for its strong play-of-color is known as _______ .
Black crystal opal
What gemstone carries thousands of years of cultural significance, especially in Asia?
Jade
Which is more valuable jadeite or nephrite?
Jadeite
What are jadeites three most important qualities?
color
transparency
texture
In addition to green what eight other colors can jadeite be?
lavender
red
orange
yellow
black
white
brown
gray
What is the trade term for the most valuable jadeite?
Imperial
What transparency is the most highly valued jadeite?
Semitransparent
Intense green.
Finest Jadeite
What country is the main polishing center for jadeite?
China
True or False:
The intense global demand for jadeite exceeds production?
true
Why are jadeite and nephrite both called jade?
The chemical differences are so subtle.
A readily available, lower-priced alternative to jadeite is ______ .
Nephrite
Gemstone jewelry that is carved from a single piece of rough is called a ________ .
holoith
In jade what is "mottling"?
An uneven distribution of color against a contrasting background
What is mountain jade?
Thick-skinned jadeite boulders
The coarsest texture category of jadeite is known as the term __________ .
new mine
The finest texture category of jadeite is known as the term _______ .
old mine
The term "relatively old mine" refers to what rexture category of jadeite?
medium
Weathered thin-skinned jadeite boulders are known as __________ .
river jade
Spots of color near the surface of a jadeite boulder, where the skin is thin enough to allow color to show through.
show points
What is type A jadeite?
natural jadeite enhanced only with a surface coating of wax.
Natural jadeite that's bleached in acid to remove undesirable staining, then impregnated with wax or polymers is called __________ .
type C jadeite
In what area was jadeite first fashioned and used as an ornamental object?
Central America
The finest quality jadeite is called __________ .
Imperial jadeite
Jadeite's finest green color is caused by _______ .
Chromium
The most valuable level of transparency in jadeite is __________ .
semitranpsrent
The toughness of jadeite is _________ .
exceptional
The finest texture category of jadeite is known as _______ .
old mine
What type is bleached and impregnated jadeite?
Type B
What type is dyed jadeite?
Type C
In Myanmar, the center of the jadeite mining district is ____________ .
Hpakan
Spots of color near the surface of a jadeite boulder, where the skin is thin enough to see through, are called ____________ .
show points
What country recently emerged as a valuable source of black jadite?
Guatemala
Polar jade is fine quality __________.
nephrite
What color is caused by the heat treatment of jadeite?
orange
Spinach jade is used to describe a color of ____________ .
nephrite
What country is a major source of nephrite?
New Zeland
What gemstone commands the highest per-carat price of all colored stones?
ruby
Where does ruby rate on the Mohs hardness scale?
9
red to slightly purplish red
med to med-dark tone
vivid saturation
Finest ruby
What trace element causes ruby to be red?
Chromium
What causes fluorescence in a ruby?
Chromium
In what type of deposits are the finest rubies found?
marble deposits
Basalt-hosted rubies have higher levels of what element?
iron
The iron in basalt-hosted rubies inhibit what?
fuorescence
What is used to treat almost all rubies?
heat
What country IMPORTS the most rubies than any other?
USA
What country is the world's largest marketing center?
Thailand
What country EXPORTS the most of the faceted commercial- quality rubies?
Thailand
Switzerland deals with what type of rubies from other countries?
high-end
Where is the most important historical ruby source?
Mogok, Myanmar
What city and country is the source for the majority of commercial-quality rubies.
Mong Hsu, Myanmar
In ancient Sanskrit ruby is called ratnaraj which means ____________ .
"king of precious stones"
The most valuable tone and saturation for ruby are __________ and __________ .
medium to medium dark tone
vivid saturation
Corundum can form only in an enviroment that is low in what element?
Silicon
Rubies that come from marble deposits are typically low in ___________ .
Iron
Ruby that originate in Thailand Cambodia and Madagascar are associated with what type of deposits?
alkali-basalt
What is the result from heat treating Mong Hsu rubies?
Eliminates dark centers or cores
The worlds largest corundum marketing center is located in what country?
Thailand
Switzerland exports rubies that are primarily ________ .
high-end
What location has supplied the world with most commercial-quality rubies since 1991?
Mong Hsu
The major source for rubies in the 1980's was what country?
Thailand
Compared to rubies from Myanmar, most Thai rubies tend to be ___________ .
darker
Rubies from Pailin, Cambodia are similar to those from what country?
Thailand
Vietnamese rubies originate in what type of deposit?
marble
Where are the Penny Lane and John Saul mines located?
Kenya
Newly discovered ruby deposits at Vatomandry and Andilamena are in what country?
Madagascar
What three trace elements in differing amounts and combinations cause most fancy sapphire colors?
iron
titanium
chromium
What type of fancy sapphire has the highest per-carat value.
padparadschas
Other than padparadschas, what color fancy sapphire also commands top prices?
fine pink
What colors can be created by heating purple sapphires?
pink or red
What location has seen an increase in yellow and orange sapphires?
East Africa
An inexpensive natural substitute for diamond is a __________ .
colorless sapphire
What is the typical corundum color change?
daylight / blue or violet
incandescent / violetish purple to strongly reddish purple
What trace element causes sapphire's color change?
Vanadium
The stars in the finest star corundums show these three characteristics ___________, ___________ and __________.
distinct
centered
uniform
The finest star corundum has a body color that provides ___________to the __________ .
strong contrast
star
What is the most valued star corundum?
star ruby
All being equal, which costs LESS, star ruby or blue star sapphire.
blue star sapphires
What area is a significant corundum source that promises to be even more productive in the future?
East Africa
The name padparadscha means _____________ .
lotus flower
What is the trade name for intensely saturated, light to medium pinkish orange to orange-pink sapphires?
padparadscha
Color-change sapphire typically changes from blue or violet to ___________ .
reddish purple
The most common number of rays in a star corundum is __________ .
six
Asterism in black star sapphire is caused by _________ .
hematite
The best quality star corundum has what type of tranparency?
semi-transparent
Which is the most prized body color in star corundum?
red
What trace element causes the pink color of corundum?
chromium
Which fancy sapphire hue regularly commands top prices?
pink
Green sappire is _______ .
readily available
Which color star sapphire is usually cut shallow due to parting?
black
What country is the major source of black sapphire?
Australia
Fancy sapphires from Montana tend to be __________ .
light in tone
The first flame fusion star rubies were produced in what time period?
1940's
Strongly saturated blue or violetish blue.
Tanzanite
Why must cutters balance tanzanite's weight retention against the quality of face-up color?
Tanzanite's strong plechroism
What treatment is used to bring out tanzanite's more attractive blue and violet hues?
heat treatment
What country is the only commercial source of tanzanite?
Tanzania
What moderately priced commercial-quality stone (when available) is more marketable than commercial-quality tanzanite?
blue sapphire
What is the most convincing tanzanite imitation?
synthetic forsterite
What characteristic determines iolites value?
predominantly blue face-up color
How can iolite be an affordable alternative to tanzanite?
It can sell for about one tenth of the price
What is the finest color-change gemstone?
Alexandrite chrysoberyl
What color-change gemstone sets the standard against which all other color-change gems are judged?
alexandrite
What trace element causes alexandrite's color-change?
chromium
daylight / green to bluish green
incandescent / red to purplish red
Alexandrite color change
In what country was a large deposit of alexandrite discovered in the early 1980's?
Brazil
What makes cat's-eye chrysoberyl the most prized chatoyant gem?
excellent hardness
durability
the sharpest cat's-eye
Why is cat's-eye chrysoberyl marketed as a man's gem?
it withstands rough wear and is subtly colored
The most economically important gem is ___________ .
tanzanite
In what area of Tanzania was tanzanite discovered?
Merelani
The name tanzanite was given to transparent blue zoisite by whom?
Tiffany & Co
Tanzanite's best color is ___________ .
strongly saturated
blue or violetish blue
Almost all tanzanite is _______ .
treated
Untreated tanzanite is typically what color?
brownish
Tanavyte is a trade name for __________ .
purple synthetic YAG
In iolite, the most valuable main face-up color is ______ .
blue
Top color iolite is ____________ .
untreated
In what year was alexandrite first discovered?
1830
What color characteristic changes during alexandrite's color-change effect?
hue
What color is top-quality alexandrite in daylight?
bluish green
The most prized chatoyant gem in the world is __________ .
cat's-eye chrysoberyl
What country is the major source for cat's-eye chrysoberyl?
Sri Lanka
Yellow to yellowish green through grayish green.
Cat's-eye chrysoberyl
The color of fine quality cat's-eye crysoberyl is ____________ .
semi transparent golden
yellow to slightly greenish yellow / brownish yellow "honey" color
What causes cat's-eye chrysoberyl's chatoyancy?
fine needle-like inclusions
What are the three factors related to the quality of cat's-eye chrysoberyl?
bodycolor
transparency
quality of cutting
What does the trade term "milk and honey" mean with cat's-eye chrysoberyl?
one side / original body color
other side / milky appearance.
Most gem tourmalines are __________ .
elbaites
Most gem tourmalines form in ___________ .
pegmatites
The world's largest producer of gem-quality tourmaline is ______ .
Brazil
The most expensive variety of tourmaline is ________ .
Parabia
What trace element causes the color in Parabia?
copper
What is the trade term for blue tourmaline?
Indicolite
What country is the largest producer of chrome tourmaline?
Tanzania
Rubellite tourmaline is colored by what element?
manganese
How are many green and blue tourmalines lightened?
heating
What treatment is used for many Parabia tourmalines?
heat
What trace element causes the color of peridot?
iron
Where is the most of the world's commercial-quality peridot mined?
Arizona
Blue zircon is colored by what treatment?
heat treatment
Metamict zircons are described as ____________ .
low zircons
Which countries produce the finest peridot?
Myanamar and Pakistan
What two groups of minerals share the same crystal structure but have slightly different chemical and physical properties.
tourmalines
garnets
Why do cutters have to fashion tourmalines in slender proportions?
elongated crystal growth
Why must cutters orient finished tourmaline gems carefully to achieve the best colors?
tourmalines strong plechroism
What country supplies the majority of the world's gem-quality toumaline?
Brazil
What are the two most important tourmaline treatments?
heating
irradiation
What country has the main sources that supply the world with most of its LARGE fine-colored peridot?
Myanmar
What state in the US supplies the world with rough for much of its commercial-quality calibrated peridot?
Arizona
What easily distinguishes colorless zircon from diamond or synthetic cubic zirconia?
strong double refraction
Why does zircon need care in handling and wear?
brittleness
What is the trade term for a vibrant green tourmaline that is colored by traces of vanadium, chromium or both?
chrome tourmaline
What is the trade term for blue tourmaline?
indicolite
Gems that show color zoning with two or more colors is known as ___________ .
parti-colored
What is the trade name for a pink to red elbaite tourmaline?
rubellite
What is the refractive nature of garnet?
single
How do gemologists classify garnets?
by their chemistry and their properties.
What do dealers base their garnets on?
color or origin
What type of garnet has properties that make it an effective and less expensive alternative to emerald?
tsavorite
What is the best color for tsavorite?
vivid green
medium to medium-dark tone
Tsavorite is colored by what trace element?
vanadium
In what area is tsavorite mostly mined?
East Africa
Name a transparent green variety of andradite?
demantoid garnet
Demantoid garnet is colored by what trace elements?
a mixture of chromium and iron
What is the most valuable orange garnet?
spessartite
Name a transparent orange to cinnamon-colored variety of the grossularite species of garnet?
hessonite
Rhodolite and most red garnets are a mixture of what two garnet species?
pyrope and almandite
Dark purplish red to light reddish purple.
Rhodolite's color range.
What is the most valuable red garnet?
rhodolite
What area has been the most important source of rhodolite since the 1960's?
East africa
What type of garnet is used in inexpensive mass-market jewelry?
dark-toned, reddish brown calibrated pyrope-almandite
Color-change garnets are comprised of a mixture of what species?
pyrope-spessartite
What trace element is the coloring agent in color-change garnet?
vanadium
In spinel, what trace element causes the strength of red in garnet?
The higher the chromium content the stronger the red
What is the most rare and valuable spinel hue?
red
What gemstone forms in the same metamorphic rock as corundum and is found in the same alluvial deposits?
spinel
Why have many people not seen a natural spinel?
Because natural spinel is rare and synthetic spinel is common
A cabochon with a curved, undercut bottom, designed to lighten the tone of the gem material is called a ___________ .
hollowback
The substitution of one chemical element for another in the crystal structure of a mineral is called _________ .
isomorphous replacement
Where is spessartite most commonly found?
pegmatite veins
Which of the following has the widest color range?
A. Rhodolite
B. Almandite
C. Spessartite
D. Grossularite
D. Grossularite
Tsavorite and hessonite are both varieties of __________ .
grossularite
All garnets have essentially the same __________ .
crystal structure
Rhodolite is a mixture of what varieties of garnet?
almandite and pyrope
Mandarin garnet has been used as a trade name for __________ .
spessartite
Dematoid was first discovered in what country?
Russia
Tsavorite is colored by what element?
vanadium
The intense red color of spinel is caused by what element?
chromium
Horsetail inclusions are found in what type of garnet?
dematoid
The most important source of rhodolite in recent years has been in what area?
East Africa
The most valuable spinel color is _________ .
red
The most desirable, vibrant, and rare blue natural spinels are colored by what elements?
cobalt and iron
Light that eventually returns to the eye after entering a gem through the crown, reflecting off its pavilion facets, and exiting back through the crown is known as __________ .
brilliance
A cutting style with triangular or kite-shaped facets that radiate from the center toward the girdle is called a __________ .
brilliant cut
A smoothly rounded polished gem with a domed top and a flat or curved base is called a _________ .
cabochon
A gem carving style in which the design, often a women's profile, projects slightly from a flat or curved surface is called a ________ .
cameo
Removing heavily included sections from gemstone rough by carefully tapping it with a small hammer is called ___________ .
cobbing
The top part of the gem above the girdle is called __________ .
the crown
The relationship of the height of a gem's crown to the depth of tis pavilion, judged by viewing its profile is called _____________ .
Crown/height to pavillion/depth ratio
Artistic gem cuts that aren't limited to specific proportions or shapes are called ____________ .
designer cuts
A wooden or metal stick that holds the preform during faceting is called a __________ .
dopstick
A device that holds the dopstick at precise angles to allow correct orientation during faceting and polishing is called a ________ .
faceting head
A free-form cut that can feature alternating curved an flat surfaces is called a __________ .
fantasy cut
The narrow section that forms the boundary between the crown and the pavilion, and functions as the gem's setting edge id called the ______ .
girdle
The process of giving approximate shape to a gemstone or producing flat planes for polishing facets is called _____________ .
grinding
A design engraved into the surface of a gemstone is called an __________ .
Intaglio
A horizontal spinning metal disk used to grind or polish a gem's facets is called a ____________ .
lap
A cutting style that combines brilliant-cut and step-cut facets is called a ____________ .
mixed cut
The lower part of a faceted gem below the girdle is called the ____________ .
pavillion
The final stage in gem cutting that produces the smoothest possible surface is called ___________ .
polishing
Rough ground to approximate shape of the finished stone; also, the act of producing this shape is called ___________ .
preform
The angles and relative measurements of a polished gem, and the relationships between them is called ____________ .
proportions
Dividing the gem rough into easily handled pieces and removing waste areas is called _____________ .
sawing
A cutting style with mainly square and rectangular facets arranged in concentric rows is called a ___________ .
step cut
The arrangement of a stone facets is called the __________ .
style
The precision and balance of the corresponding parts of a finished gem is called it's __________ .
symmetry
The facet at the top of the crown, usually the largest facet on the stone is called the ___________ .
table facet
Which type of rough is usually faceted?
transparent
To retain as much weight as possible from rare, high-quality rough, cutters would most likely vary the __________ .
proportions
Translucent to opaque rough is often cut into what type of cut?
cabochon
A carved design that projects slightly from a flat or curved surface is called ____________ .
a cameo
Colored stones cut flat with shallow pavilions usually have areas of lower color intensity called _______ .
windows
A cutter can darken the color of a pale stone by cutting a ___________ .
deep pavilion
To judge brilliance, view the stone in what direction?
face-up
What adds weight to a step cut?
excessive buldge
Colored stones that rate "fair" for brilliance have what percentage?
between 25 and 40 percent brilliance
The pattern of dark vertical lines or bands shown by certain gems when viewed through a spectroscope is called ______________ .
absorption spectrum
Which element does chromium substitute for that causes ruby's red?
aluminum
A gem colored by the element that is part of its basic chemistry is called ______________ .
idiochromatic
Which element causes the color of both almandite and peridot?
iron
The process where electrons that selectively absorb light are passed back and forth between neighboring ions is known as ______________ .
intervalance charge transfer
Which components of a transition element's atoms can produce color in gems?
electrons
Which element causes the finest reds and greens in gemstones?
chromium
Which transition element causes a greater variety of gem colors than any other?
iron
In many blue sapphires, the intervalence charge transfer that causes the color is between what two elements?
iron and titanium
When a gem's crystal structure splits light into two rays that each travel at a slightly different speed and direction, it's called ____________ .
double refraction
What is the only type of gem that can show pleochroism?
doubly refractive
Which gem can show three pleochroic colors?
andalusite
kyanite
tanzanite
iolite
What phenomenon shows a broad color flash?
labradorescence
Adularescence is caused by what?
A scattering of light as in moonstone
The best-known and most valuable chatoyant gem is cat's-eye ____________ .
chrysoberyl
The cloudy bluish white light in a moonstone, caused by scattering of light.
adularescence
A gem colored by trace elements in its crystal structure.
allochromatic
Crossing of chatoyant bands, creating a star in the dome of a cabochon.
asterism
A glittery effect caused by light reflecting from small flat inclusions within a gemstone.
aventurescence
A small defect in the atomic structure of a material that can absorb light and give rise to a color.
color center
A special kind of interference phenomenon that breaks up white light and give rise to a color.
diffraction
Emission of visible light by a material when it's stimulated by ultraviolet light.
fluorescence
A gem colored by an element that is an essential part of its chemical composition.
idiochromatic
Interaction of two light rays traveling the same path.
interference
A rainbow effect created when light is broken up into spectral hues by thin layers.
iridescence
A broad flash of color in labradorite feldspar that disappears when the gem is moved.
labradorescence
A two-toned effect seen when a chatoyant gem is positioned at right angles to a light source.
"milk and honey"
Direction of single refraction in a doubly refractive gem.
optic axis
Iridescence seen in some natural and cultured pearls and mother-of-pearl.
orient
An unusual optical effect displayed by a gem.
phenomenon
The flashing rainbow colors in opal.
"play-of-color"
When a gem shows different body-colors from different cystal directions.
pleochroism
Change in speed and possible change in direction of light as it travels from one material to another.
refraction
Process by which a material absorbs some components of visable light and transmits others.
selective absorption
When a gem's crystal structure doesn't change incoming light other than by refraction and absorption.
single refractive
Elements that can selectively abrorb some wavelengths of visible light and produce color in gems.
Transition elements
Which gemstone occurs in almost every color?
Tourmaline
The first impression of an object's basic color is its ___________ .
hue
Generally, cool-colored hues with low saturation look ____________ .
grayish
Use trade terms that imply geographic origin only if the ________________ .
gem's actual source is known
Which trade term describes certain tourmalines?
A. Paraiba
B. Kashmir
C. Sandawana
D. Mozambique
A. Paraiba
What is the GIA Colored Stone Grading System's abbreviation for a "slightly purplish red hue" ?
slpR
In practice, what GIA Colored Stone Grading levels apply to grading transparent colored stones?
2 through 8
A see-through area cut in a transparent gemstone's bodycolor that usually results from the way the gem was cut is called _____________ .
a window
A window usually differs from the rest of the stone in _______________ .
saturation
Extinction results from ____________ .
deep pavilions
The color of the background for grading a colored stone should be ______ .
neutral.
What type of lighting is best for grading color in a colored stone?
daylight-equivalent fluorescent
Higher levels of saturation are usually found in stones with ___________ .
medium to medium-dark tones.
What two coloring agents are usually responsible for color change in gemstones?
chromium and iron
Emission of visable light by a material when it's exposed to invisable ultraviolet radiation is called __________ .
fluorescence
You should judge a gemstone's beauty and value only by comparing it to what?
A sample of its own species or variety.
Cutting compromises that save weight can also cause what __________, __________ or ___________ .
windows
extinction
both
What do you use, in a buying situation, when you cannot control the lighting conditions?
comparison stones or color samples
A laboratory-created gem with essentially the same chemical composition, crystal structure, and properties as its natural counterpart is called a _____________ .
synthetic
The two main types of processes for synthetic gem production are melt and ____________ .
solution
Low cost and high volume characterize which synthetic process?
flame fusion
What synthetic process developed rapidly due to laser research in the late 1960's?
pulling
What process uses a heating unit to pass over a rotating solid rod of chemicals until it forms a synthetic crystal?
floating zone
What process dissolves nutrients in chemicals to form synthetic crystals?
flux growth
The crucibles that work best for flux growth are made of what material?
platinum
The hydrothermal growth process is the only method used to produce which synthetic gem?
quartz
What synthetic process uses an autoclave?
hydrothermal growth
Synthetic opal is grown using microscopic silica spheres that are produced by _________ .
precipitation
What process involves heating finely ground powder, sometimes under pressure, to produce a fine-grained solid material?
ceramic
Synthetic turquoise is most likely produced by what process?
ceramic
The flux used in the flux process is a solid material that, when molten it ____________ .
disolves other materials
The hydrothermal synthetic process requires what?
a pressurized steel container and crushed chemical ingredients
A snakeskin structural pattern is typical of what synthetic?
synthetic opal
A process in which powdered chemicals are dropped through a high-temperature flame onto a rotating pedestal to produce a synthetic crystal.
flame fusion
A melt process where a heating unit passes over a rotating solid rod of chemicals until it forms a synthetic crystal.
floating zone
A process in which nutrients dissolve in heated chemicals, then cool to form synthetic crystals.
flux growth
A process in which nutrients disolve in a water solution at high temperature and pressure, then cool to form synthetic crystals.
hydrothermal growth
A synthetic crystal growth method in which the chemical mixture is melted, then recrystalized.
melt process
A synthetic crystal growth method that uses cooling pipes around an interior of melted chemical ingredients.
skull melt
A growth method in which the synthetic crystal grows from a dissolved chemical mixture, sometimes at high temperatures an pressure.
solution process
A synthetic growth method that starts WITHOUT a seed crystal.
spontaneous nucleation
Most synthetic gems are produced by either what two processes?
melt
solution
A mass of tiny, randomly oriented crystals.
aggregate
A smooth, flat break in a gemstone parallel to planes of atomic weakness, caused by weak or few bonds between atoms, or both.
cleavage
A curved and ridged fracture in a gemsotne, extending from the surface inward.
conchoidal fracture
An aggregate made up of individual crystals detectable only under very high magnification.
cryptocrystalline
How heavy an object is in relation to its size.
density
A gemstones ability to withstand wear, heat and chemicals.
durability
Any break in a gem other than cleavage or parting.
fracture
The characteristic external crystal shape or form of a mineral.
habit
How well a gemstone resists scratches. Usually expressed in terms of the Mohs scale, with diamond the harderst (10) and talc the softest (1).
hardness
An aggregate made up of individual crystals visable under magnification.
microcrystalline
A flat break in a gemstone caused by concentrated included minerals parallel to a twinning plane.
parting
How well a gemstone resists light, heat, and chemicals is called ___________ .
stability
Ratio of the weight of a matrial to the weight of an equal volume of water.
specific gravity
Damage caused by sudden, extreme temperature changes.
thermal shock
A hollow cavity in a gem, filled with a liquid, a gas, and one or more crystals.
Three-phase inclusion
Atoms of a gem that aren't part of its essential chemical composition.
trace element
Change in a gem's crystal direction during or after growth.
twinning
Location of a change in crystal growth direction.
twinning plane
A hollow cavity in a gem, usually filled with a liquid AND a gas.
Two-phase inclusion
The smallest group of atoms with both the characteristic chemical composition and crystal structure of a mineral.
unit cell
A unit cell defines a mineral's ___________ .
basic identity
If a crystal grows in a flux that is highly saturated with the necessary elements it tends to be ___________ .
small
What aggregate's crystals are visible only with magnification greater than a standard gemological microscope?
cryptocrystalline
Which is classified in the orthorhobic system?
A. Beryl
B. Topaz
C. Garnet
D. Corundum
topaz
Which element causes the red in ruby and the green in emerald?
chromium
What type of twinning is caused by enviromental change after the gem forms?
polysynthetic
What type of twinning looks as if two crystal halves are mirror images?
contact
Needles of actinolite found in emerald are classified as what?
inclusions
A two-phase inclusion is a cavity in a gem that's typically filled with a ___________ and a __________ .
liquid
gas
Atoms in a gem that are not part of its essential chemical composition are called what?
trace elements
The trace elements that cause corundum's blue are ____________ and ________ .
iron
titanium
An object's weight in relation to its size is called its ____________ .
density
Which gems are cryptocrystalline?
A. opal and amethyst
B. nephrite and jadeite
C. chalcedony and turquoise
chalcedony and turquoise
Rough spinel often occurs as what type of crystals?
twinned
Many fashioned rubies have shallow proportions because they're cut from what type of crystals?
flat
What are the three different ways a gem can break?
cleavage
parting
fracture
A gem's price divided by its carat weight is called ___________ .
per-carat price
The international unit of measurement for gem weight is the _________ .
metric carat
Individual stone prices are referred to as __________ .
unit prices
How many points are in a metric carat?
100
A metric carat equals __________ gram(s).
0.20 gram
How are most colored stones sold?
by weight
What category of colored stone is often sold per piece?
small, inexpensive
Sieves are most useful for sorting round gems with diameters that are what size?
3mm and below
When you first start to count a large pile of small gems, it's best to seperate them into groups of how many?
5
The color of a sorting pad should be ___________ .
neutral
Colored stones with higher value usually have what color characteristics?
medium to medium-dark tone
vivid saturation
Amber is actually _____________ .
hardened tree resin
Immature amber is known as _____________ .
copal
What is the most valuable amber color?
red
What type of coral is a calcium carbonate?
pink
What is coral's most valuable color?
red
What are the two conchiolin coral colors?
black
golden
What treatment can create a golden color from black coral?
bleaching
What organic shows a structure called "engine turning" which looks like lines created on a lathe?
ivory
What animal's tusk produces the most valuable ivory?
elephant
"Paua" is a Maori name for __________ .
albalone shell
Tortise shell is composed of what?
protein
Jet is an ornamental form of ___________ .
lignite coal
What country is the major source for jet?
England
Name a natural glass gem.
moldavite
Where is the only source of benitoite located?
California
What are the circular marks sometimes left in amber when treaters heat and oil it?
sun spangles
How old does tree resin have to be before it is called amber?
1 million years old
Nearly all trade in new elephant ivory has been illegal since what time period?
mid 1970's
What is the most difficult shape to produce in pearl culturing?
round
What is the name of the largest gem-quality natural pearl?
Dudley
Pearl colors are usually _________ .
low in saturation
In the trade, Tahitian cultured perals witha dark green-gray to blue-gray bodycolor and rose' to purple overtones are called ____________.
peacock
What overtone color increases the value of akoya cultured pearl with white bodycolor?
rose'
When mollusks live in cooler water, they form pearls with ___________ .
thicker nacre
Pearls that show noticeable surface characteristics are considered ____________ blemished.
severely
The best way to clean pearls is with ____________ .
warm, mild soapy water
The nacre quality classification described as "Nucleus not noticeable, no chalky appearance" is classified as __________ .
acceptable
The matching level that describes a group of pearls that have minor variations in uniformity is considered ____________ .
good
Farmers of every cultured pearl type does this after harvest.
wash
dry
sort
Almost all akoya and Chinese freshwater pearls are __________.
bleached
Usually, the diameters of the cultured pearls in a hank vary from each other by nor more than how many millimeters?
0.5mm
"Essence d'orient" is a mixture of ___________.
fish scales and varnish
What happens when saltwater cultured pearls are exposed to gamma rays?
the bead nucleus darkens
All pearls display bodycolor, and some also have what characteristics?
overtone
orient
both
A pearl with one or more grooved ridged rings all the way around it is called a ___________.
circled pearl
A mixture of clear varnish and fish scales used in making imitation pearls is called _________ .
essence d'orient
A cultured pearl with a hole drilled all the way through; sometimes called drilled-through is called ___________.
full-drilled
A cultured pearl with a hole drilled halfway through to permit mounting on a post is called ______________.
half drilled
A procedure that includes cleaning buffing and sometimes bleaching, done to make cultured pearls presentable and appealing is called ___________.
process
Blemishes or irregularities confined to a pearl's surface is called a ________ .
surface characteristic
A cultured pearl with any unsightly potion cut or ground off is called a ____________.
three-quarter-cut
Features used to judge the quality and value of pearls are called __________.
value factors
Most gemstones form in the __________.
continental crust
Rocks altered by heat and pressure are ___________.
metamorphic
What gem can crystallize in volcanic rock from gasses released by magma?
Vietnamese ruby
Where is the key locality for hydrothermal gems?
Ouro Preto, Brazil
What gems form by metamorphism?
ruby
emerald
alexandrite
tanzanite
tsavorite
Heat and pressure transform limestone into ___________.
marble
A deposit where gems are found in the rock that carried them to the earth's surface is called __________.
a primary deposit
A deposit where gems eroded from the source rock and remained in place nearby is called an __________.
eluvial deposit
What is a workable alluvial deposit of gem minerals with economic potential called?
a placer
Kunzite is most often found in association with what?
tourmaline and beryl in pegmatite
Mynamar's famous Mogok ruby deposits were formed by ___________.
regional metamorphism
Pegmatite gems are rich in volatile elements like _________, __________, and __________.
beryllium, boron and lithium
Most of the gems in Tanzania's Umba River Valley are found in what type of deposits?
placer
Emerads are rarely found in placer deposits because they're __________.
too soft
A deposit where gems are eroded from their source rock, then transported away from the source and further concentrated.
alluvial
Localized changes caused by an igneous intrusion that takes place where the magma meets the surrounding rock. New minerals may form due to temperature changes or introduction of fluids from the magma.
contact metamorphism
The earth's innermost layer is called the ________.
mantle
The surface and outermost layer of the earth is called the _______.
crust
Rock formed by the crystallization of molten material.
igneous rock
A large mass of igneous rock that crystallizes underground without reaching the surface is called an __________.
intrusion
A general term for molten rock.
magma
The layer between the earth's crust and its core is called the _____________.
mantle
The circulation in the mantle that drives the movement of the earth's plates is called ____________.
mantle convection
Rock altered by heat and pressure, or by heated fluids from magma is called a ____________.
metamorphic rock
An igneous rock formed by cooling, once-molten granite that follows fractures in its surrounding rock. It may contain very large drystalsm and its shape is often thin and contorted is called _____________.
pegmatite
A section of the earth's rigid outer crust is called a __________.
plate
The study of the formation, structure, and movement of the plates of the earth's crust is called ___________.
plate tectonics
Crystallization of minerals from a gas is called __________.
pneumatolysis
Gems found in the rock that carried them to the surface are found in this deposit.
primary
Changes in rock type and minerals over a wide area caused by heat and pressure of large-scale geological events is called _____________.
regional metamorphism
A constant formation and recycling process that creates new rock from old is called the ___________.
rock cycle
Gems found away from their primary source are called ___________.
secondary deposit
Rock produced from the eroded and weathered remains of existing rocks are called ____________.
sedimentary
A process that occurs when two of the earth's plates collide, forcing one under the other is called ____________.
subduction
A mineral deposit that occupies an existing fissure or fracture in the rock is called a ___________.
vein
Pertaining to igneous activity at the earth's surface, where magma erupts through a volcano or a fissure is called ________.
volcanic
A "foreign crystal" that formed in unrelated tocks and was brought to the surface as a passenger in magma is called a ____________.
xenocryst
Geological conditions during ___________ ___________ are favorable for gem formation.
mountain building
Igneous rocks, large crystals indicate slow cooling, while small crystals indicate _____________.
quick cooling
A majority of the largest and most perfect gem crystals come from _________.
pegmatites
What can transfer minerals in solution and redeposit them in veins to form gems?
superheated, pressurized water
Written information on dyeing gems dates back to about what year?
200BC
Heat can lighten amethyst's purple by _________.
causing changes in color centers
Creating asterism with heat treatment is most common in what gemstone?
synthetic corundum
What coloring agents do treaters use during lattice diffusion to create a shallow layer of blue color in corundum?
titanium oxide and iron oxide
How deep is the color layer that lattice diffusion with titanium or chromium creates in corundum?
0.01mm to 0.50mm
What agent can create a shallow layer of asterism when it's introduced below the surface of a corundum cabochon by lattice diffusion?
titanium oxide
For effective clarity enhancement, the material used to fill a gem's fractures must have nearly the same?
refractive index as the gem
After irradiation, which gem's color is stable under normal wearing conditions?
orange sapphire
What treatment is often used with jadeite?
bleached and polymer impregnated
The Zachery method is a treatment that is applied to what gemstone?
turquoise
Quartz or topaz with a thin layer of gold deposited on the surface is known as ___________.
aqua aura
Heat treatment in a reducing environment does what to sapphire?
deepens the blue color
Treaters use "sugar treatment" to enhance what gemstone?
opal
A treatment in which a gem is exposed to high temperatures and chemicals to allow penetration of color-causing elements is called ____________.
lattice diffusion
An oxygen poor environment that surrounds a gem during heat treatment, causing it to lose oxygen is called a __________.
reducing environment
Heating wrapped opal until smoke or ash penetrates its surface to darken it and bring out its play-of-color is called ____________.
smoke treatment
Soaking an opal in a hot sugar solution and then in sulfuric acid to darken it and bring our its play-of-color is called ___________.
sugar treatment
Altering a gem's appearance by applying backings, coatings or coloring agents like paint is called ___________.
surface modification
What are the most commonly heat treated gemstones?
corundum zircon
topaz tanzanite
aquamarine amber
Heat treatment can alter color and create or eliminate ____________ and ___________.
phenomena
inclusions
Lattice diffusion with titanium produces what?
a shallow layer that can be removed with minor polishing.
Lattice diffusion with what element may penetrate the entire stone?
beryllium
Almost all emeralds on the market today are what?
fracture filled
Common irradiated gems include ____________.
topaz tourmaline
cultured pearl
What is one of the oldest gem treatments?
dyeing
Commonly dyed gems include _______________.
cultured pearl chalcedony coral
lapis lazuli
A characteristic or irregularity confined to the surface of a polished gemstone is called a ___________.
blemish
An angular, hollow space that resembles a mineral inclusion is called a ______________
negative crystal
A general term for a break in a stone is called a ____________.
feather
An inclusion with the most negative impact on a colored stone's clarity would be located where?
under the table
Which colored stone clarity type are the gems usually eye-clean?
Type I
The highest clarity grade for colored stones is ___________.
eye-clean
The term "silk" describes _____________.
a group of fine needle-like inclusions
"Fingerprints" are considered what?
fractures
What gems would be classified as Type III?
emerald
red beryl
watermelon tourmaline
In which colored stone clarity grades do the definitions vary for each clarity type?
moderately included
What clarity characteristic would usually have the greatest impact on a gem's marketability?
a large unhealed feather
Gems that are usually eye-clean include ___________.
spodumene
yellow beryl
aquamarine
Inclusions are important to gemologists because they do what?
help seperate natural from synthetic gems
Growth zoning in a colored stone is evidence of what?
crystal growth
Two factors that determine an inclusion's impact on a gem's value are __________ and___________.
crystal system and size
Tiny nicks and pits caused by wear and damage to a gem's facet edges or culet is called an ___________.
abrasion
An opening that extends into a gem from the surface is called a ___________.
cavity
A damaged area of a gem, usually near a girdle is called a ____________.
chip
Any hazy or milky area that cannot be described as a feather, fingerprint, or group of included crystals or needles is called a ____________.
cloud
A long, thin inclusion that can be a solid crystal or a hollow tube that might be filled with liquid or gas is called a _____________.
needle
Minute inclusion enclosed within a gem; can occur singly or in groups called clouds is called a _____________.
pinpoint
Contrast between an inclusion and its host gem is called ___________.
relief
A group of fine needle-like inclusions is called ____________.
silk
What are the five factors that determine influence of clarity characteristics on marketability?
nature
size
number
position and relief
Most gems are __________.
minerals
To be a gem a mineral must be what?
beautiful
durable
rare
What is the number one stone by value imported into the US?
emerald
Lacking a crystal structure.
amorphous
The basic structural element of all matter.
atom
A substance that consists of atoms of only one kind.
chemical element
Regular, repeating internal arrangement of atoms in a material is called its ___________.
crystal structure
A broad gem category based on chemical compostition and crystal structure is called __________.
gem species
A subcategory of species, based on color, transparency or phenomenon is called a ___________.
gem variety
A family of gems from several closely related mineral species is called a ______________.
group
Composed of, or arising from, non-living matter is considered ________.
inorganic
A natural, inorganic substance with a characteristic chemical composition and usually characteristic structure is called a __________.
mineral
Produced by, or derived from, a living organism is called ____________.
organic
A natural material composed of masses of mineral crystals of one or more kinds is called a _________.
rock
A mineral that contains the elements silicon and oxygen is called a __________.
silicate
What is Myanmar's most important gem export?
ruby
Which location produces the majority of rubies that end up in mass-produced jewelry?
Mong Hsu
What is the trade term that describes a mixture of gem qualities that represents unsorted production from a particular mine?
mine run
What term describes a specific rough gemstone quality range, usually determined by color, size, clarity, and price?
grade
Where is rough from Mogok brought into Thailand?
Mae Sot
Where is rough from Mong Hsu brought into Thailand?
Mae Sai
In mining terms, the theft of a mine's production by its workers is known as __________.
high grading
A quantity of stones, sometimes of similar size and quality, from a single mine or from many different sources is called ___________.
parcel
What is the main cutting center in Thailand?
Chantaburi
Materials cut free-size are usually __________.
large important stones
Gemstone sizes cut to fit standard mountings are known as ________.
calibrated sizes
The market sector where better-quality gemstones are used in well-finished, moderately priced jewelry is known as the _____________.
middle market
What term describes a random sample from a parcel of gemstones often used to access the parcel's overall quality?
cut
What is the term for buying an entire parcel of gems, or a substantial part of it?
Lot price
What is the term for a premium price for selecting stones from a parcel?
pick price
Aragonite is a crystallized form of ___________.
calcium carbonate
What year did Kokichi Mikimoto begun culturing whole pearls?
1908
What industry directly contributed to the decline of the natural pearl industry?
oil
The first South Sea cultured pearl farm was founded in what country?
Australia
Saltwater whole cultured pearls grow from a ____________.
Mantle-tissue piece and a bead nucleus.
A great majority of freshwater whold cultured pearls grow from a ___________.
mantle-tissue piece only
In the early 1990's, oysters in many important Japanese cultured pearl farming areas began to ____________.
die off massively in large numbers
The four major types of whole pearls are ______, ________, __________ and ________.
Akoya South Sea
Freshwater Tahitian
South Sea cultured pearls are produced principally in Australia, Indonesia and the __________.
Philippines
The oyster used to grow Tahitian cultured pearls is _____________.
Pinctada margaritifera
The nacreous layer inside a pearl-bearing mollusk's shell is called ___________.
mother-of-pearl
What country produces the most freshwater cultured pearls?
China
A number of similar cultured pearl strands bundled together is called a ___________.
hank
Seed pearls are _________.
very small natural pearls
Common name for the Pinctada fucata oyster and the natural or cultured pearls it produces.
Akoya
A crystallized form of calcium carbonate found in nacre.
Aragonite
A bead used as the core of a cultured pearl, usually made from a freshwater mussel shell.
bead nucleus
A non-nacreous natural "pearl"
Calcareous concretion
The organic "glue" in nacre that holds aragonite platelets together.
Conchiolin
A cultured pearl grown around a nucleus glued under the mantle tissue inside a mollusk's shell.
cultured blister-pearl
A pearl formed as the result of human intervention in the formation process.
cultured pearl
The reproductive organ that produces eggs in females and sperm in males.
gonad
Describes mollusks bred in laboratory tanks and grown in protected areas rather than collected as adults in the wild.
hatchery-bred
An assembly composed of a nacre dome, filler, and a mother-of-pearl backing.
Mabe'
The organ that lines the mollusk's shell encloses its soft body, and contains the cells that form pearl sacs and secrete nacre.
Mantle
A small square of mantle tissue cut from a donor mollusk and implanted in a host mollusk with or without a bead.
mantle-tissue piece
The nacreous layer inside a pearl-bearing mollusk's shell.
mother-of-pearl
A natural substance produced by pearl-bearing mollusks to make pearls.
nacre
Tissue that encloses an implanted bead nucleous and mantle-tissue piece, or the piece alone, and secretes nacre to form a cultured pearl.
pearl sac
A company that prepares cultured pearls for the market.
processor
Chinese freshwater cultured pearls shaped and textured like rice grains.
rice pearls
What country produces an overwhelming majority of the world's freshwater cultured pearls.
China