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GIA Colored Stones

A natural inorganic substance with a characteristic chemical composition and usually characteristic crystal structure is a Mineral
A substance that consists of atoms of only one kind is a chemical element
Most gems are minerals
A natural material that’s made up of a mass of one or more kinds of mineral crystals is a rock
Which of the following is amorphous? A. Beryl B. Amber C. Garnet D. Jadeite B. Amber
A broad gem category based on chemical composition and crystal structure is a gem species
Which of the following is a gem variety? A. Beryl B. Garnet C. Andradite D. Demantoid Demantoid
Which group does almandine belong to? Garnet
The world’s largest gem-consuming market is United States
Synthetic gem materials are not minerals
Many colored stones are mined by independent miners using small-scale mining methods
Media attention in the 1990s regarding its treatment reduced consumer confidence in emerald
Most of the gems in Tanzania’s Umba River Valley are found in placer deposits
Which is a key locality for hydrothermal gems? Ouro Preto, Brazil
Which gem can crystallize in volcanic rock from gasses released by magma? Red beryl
A deposit where gems are found in the rock that carried them to the earth’s surface is called primary
Which type of deposit is usually the most profitable for colored stone mining? Secondary
Which gem forms by metamorphism? Tanzanite
Most gemstones form in the continental crust
Which is a workable alluvial deposit of gem minerals with economic potential? Placer
Pegmatite gems are rich in volatile elements like beryllium, boron, and lithium
Heat and pressure transform limestone into marble
Kunzite is most often found in association with Tourmaline, beryl, and kunzite are all found in association with pegmatites
Emeralds are rarely found in placer deposits because they’re too delicate to withstand abrasion
Rocks altered by heat and pressure are metamorphic
Which is a deposit where gems eroded from the source rock and remained in place nearby? Eluvial
Myanmar’s famous Mogok ruby deposits were formed by regional metamorphism
The trace elements that cause corundum’s blue are iron and titanium
Atoms in a gem that are not part of its essential chemical composition are trace elements
Many fashioned rubies have shallow proportions because they’re cut from flat crystals
A two-phase inclusion is a cavity in a gem that’s typically filled with a liquid and a gas
Rough spinel often occurs as twinned crystals
Needles of actinolite found in emerald are classified as inclusions
Which type of twinning is caused by environmental change after the gem forms? Polysynthetic
Which gems are cryptocrystalline aggregates? Chalcedony and turquoise
Which element causes red in ruby and green in emerald? Chromium
Which aggregate’s crystals are visible only with magnification greater than a standard gemological microscope’s? Cryptocrystalline
If a crystal grows in a flux that is highly saturated with the necessary elements, it tends to be small
An object’s weight in relation to its size is called its density
A unit cell defines a mineral’s basic identity
Which is classified in the orthorhombic crystal system? topaz
Which type of twinning looks as if two crystal halves are mirror images? contact twins
The pattern of dark lines or bands shown by certain colored gems when viewed through a spectroscope is called absorption spectrum
Which element does chromium substitute for to cause ruby’s red? Aluminum
Which element causes the color of both almandite and peridot? Iron
In many blue sapphires, the intervalence charge transfer that causes the color is between iron and titanium
What is the only type of gem that can show pleochroism? Doubly refractive
Which components of a transition element’s atoms can produce color in gems? Electrons
Which phenomenon is a broad color flash? Labradorescence
Adularescence is caused by scattering of light
Which gem can show three pleochroic colors? iolite
The process where electrons that selectively absorb light are passed back and forth between neighboring impurity ions is known as... charge transfer
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
The best-known and most valuable chatoyant gem is cat’s-eye chrysoberyl
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
A gem colored by an element that’s part of its basic chemistry is called IDIOCHROMATIC
Synthetic opal is grown using microscopic silica spheres that are produced by precipitation
A snakeskin structural pattern is typical of synthetic opal
Synthetic turquoise is most likely produced by which process? Ceramic
Which synthetic process uses an autoclave? Hydrothermal growth
The hydrothermal synthetic process requires a pressurized steel container and crushed chemical ingredients
Which process dissolves nutrients in chemicals to form synthetic crystals? Flux growth
The two main types of processes for synthetic gem production are melt and solution
Low cost and high volume characterize which process? Flame fusion
Which process involves heating finely ground powder, sometimes under pressure, to produce a fine-grained solid material? Ceramic
A laboratory-created gem with essentially the same chemical composition, crystal structure, and properties as its natural counterpart is a synthetic
Which synthetic process developed rapidly due to laser research in the 1960s? Pulling
The hydrothermal growth process is the only method used to produce which synthetic gem? Quartz
The crucibles that work best for flux growth are made of platinum
Which process uses a heating unit to pass over a rotating solid rod of chemicals until it forms a synthetic crystal? Floating zone
The flux used in the flux process is a solid material that when molten dissolves other materials
Heat can lighten amethyst’s purple by causing changes in color centers
Heat treatment in a reducing environment deepens blue color in sapphire
Which of these is considered a gem treatment? Fracture filling
Written information on dyeing gems dates back to about 200 bc
Creating asterism with heat treatment is most common in synthetic corundum
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
Jadeite is often bleached and polymer impregnated
For effective clarity enhancement, the material used to fill a gem’s fractures must have nearly the same refractive index as the gem
The Zachery Method is a treatment applied to turquoise
What coloring agents do treaters use during lattice diffusion to create a shallow layer of blue color in corundum? Titanium oxide and iron oxide
Treaters use sugar treatment to enhance opal
Which gem is commonly heat-treated? Amber
After irradiation, which gem’s color is stable under normal wearing conditions? Golden beryl
How deep is the color layer that lattice diffusion with titanium or chromium creates in corundum? 0.01 mm to 0.50 mm
Quartz or topaz with a thin layer of gold deposited on the surface is known as aqua aura
Which location produces the majority of rubies that end up in mass-produced jewelry? Mong Hsu
Which trade term describes a mixture of gem qualities that represents unsorted production from a particular mine? Mine run
Which of the following is a premium price for selecting stones from a parcel? A. Lot price B. Pick price C. Grade price D. Parcel price Pick price
Which term describes a random sample from a parcel of gemstones, often used to assess the parcel’s overall quality? pick
Which term describes a specific rough gemstone quality range, usually determined by color, size, clarity, and price? grade
Which of these is a cutting center for colored stones in Thailand? A. Pailin B. Mogok C. Mong Hsu D. Chantaburi Chantaburi
Materials cut free-size are usually large, important stones
Where is rough from Mong Hsu brought into Thailand? Mae Sai
Which of the following is a quantity of stones, sometimes of similar size and quality, from a single mine or from many different sources? A. Parcel B. Mine lot C. Mine run D. Production run Parcel
Gemstone sizes cut to fit standard mountings are known as calibrated sizes
Where is rough from Mogok brought into Thailand? Mae Sot
In mining terms, the theft of a mine’s production by its workers is known as high grading
Which of the following is a price for buying an entire parcel of gems, or a substantial part of it? A. Lot price B. Cut price C. Pick price D. Grade price Lot price
The market sector where better-quality gemstones are used in well-finished, moderately priced jewelry is known as the middle market
What is Myanmar’s most important gem export? Ruby
The first impression of an object’s basic color is its HUE
Emission of visible light by a material when it’s exposed to invisible ultraviolet radiation is fluorescence
Use trade terms that imply geographic origin only if the gem’s actual source is known
A see-through area in a transparent gemstone’s bodycolor that usually results from the way the gem was cut is called a window
Higher levels of saturation are usually found in stones with medium to medium-dark tone
What type of lighting is best for grading color in a colored stone? Daylight-equivalent fluorescent
Which trade term describes certain tourmalines? Paraíba
Which gemstone occurs in almost every color? Tourmaline
Extinction results from deep pavilions
Which abbreviation does the GIA Colored Stone Grading System use for a slightly purplish red hue? slpR
In practice, what GIA Colored Stone Grading tone levels apply to grading transparent colored stones? 2 through 8
Generally, cool-colored hues with low saturation look grayish
A window usually differs from the rest of the stone in saturation
What two coloring agents are usually responsible for color change in gemstones? Chromium and vanadium
The color of the background for grading a colored stone should be neutral
Which type of rough is usually faceted? Transparent
Removing heavily included sections from gemstone rough by carefully tapping it with a small hammer is known as cobbing
Which is a carved design that projects slightly from a flat or curved surface? Cameo
Which cutting stage has the greatest impact on the value of the finished gem? Preforming
To judge brilliance, view the stone face-up
The purpose of most variations in a colored stone’s face-up outline is to save weight
Colored stones that rate “fair” for brilliance have between 25 and 40 percent brilliance
Which is most likely to undergo cobbing? Commercial-quality amethyst rough
Excessive bulge on a step cut adds weight
Rough that’s ground to the approximate shape of the finished stone is called preform
Colored stones cut flat with shallow pavilions usually have areas of lower color intensity called windows
To retain as much weight as possible from rare, high-quality rough, cutters would most likely vary proportions
Which colored stone variety has cutting challenges due to vulnerable cleavage planes? Tanzanite (Tanzanite has two directions of cleavage)
Translucent to opaque rough is often cut into a cabochon
Cutters can darken the color of pale stones by cutting a deep pavilion
In which colored stone clarity type are the gems usually eye-clean? Type I
Inclusions are important to gemologists because they can help separate natural from synthetic gems
Fingerprints are partially healed fracture planes
The term “silk” describes a group of fine, needle-like inclusions
An inclusion with the most negative impact on a colored stone’s clarity would be located under the table
A general term for a break in a stone is feather
Which of these clarity characteristics would usually have the greatest impact on a gem’s marketability? A. A cavity on its pavilion B. A large, unhealed feather C. A small, dark crystal under its crown facets D. A low-relief liquid inclusion under its A large, unhealed feather
An angular, hollow space that resembles a mineral inclusion is called a negative crystal
Gems that are usually eye-clean include spodumene, yellow beryl, and aquamarine
In which of the following colored stone clarity grades do the definitions vary for each clarity type? Moderately included
Which of these gems is classified as Type III? A. Ruby B. Topaz C. Emerald D. Chrysoberyl Emerald
The highest clarity grade for colored stones is eye-clean
A characteristic or irregularity confined to the surface of a polished gemstone is a blemish
Two factors that determine an inclusion’s impact on a gem’s value are position and relief
Growth zoning in a colored stone is evidence of crystal growth
If an emerald weighs 3.50 carats and the stone’s cost is $10,500.00, what is its per-carat price? $3,000.00 Divide $10,500.00 (price of the gem) by 3.50 cts. (carat weight)
Most colored stones are sold by weight
A metric carat equals 0.20 gram
The international unit of measurement for gem weight is the metric carat
When you first start to count a large pile of small gems, it’s best to separate them into groups of 5
What category of colored stone is often sold per piece? Small, inexpensive
If a parcel of sapphires weighs 382.00 cts. and the per-carat price is $80.00, what is the total cost of the parcel? $30,560.00 Multiply the parcel’s carat weight by the price per carat
Individual stone prices are referred to as unit prices
Sieves are most useful for sorting round gems with diameters 3 mm and below
What is the cost of a ruby that weighs 5.76 cts. and has a per-carat price of $5,500.00? $31,680.00 The price of this ruby (or its unit price) is $31,680.00. Multiply 5.76 cts. (carat weight) by $5,500.00 (per-carat price)
A gem’s price divided by its carat weight is called per-carat price
Colored stones with higher values usually have medium to medium-dark tone and vivid saturation
The color of a sorting pad should be neutral
If a parcel of amethysts contains 1,000 stones and weighs a total of 1,542.00 cts. with a cost of $0.75 per carat, what is the unit price? $1.16 Unit price is $1.16 x 1,542.00 cts. (parcel total carat weight) x $0.75 (price per carat) for the parcel price of $1,156.50. Divide $1,156.50 (parcel price) by 1,000 (total number of stones in parcel) for the unit price of $1.1565 rounded to $1.16
How many points are in a metric carat? 100
Ruby deposits in Thailand and Cambodia are associated with alkali-basalt
The world’s largest corundum marketing center is Thailand.
Rubies that come from marble deposits are typically low in iron
Compared to rubies from Myanmar, most Thai rubies tend to be darker
In the early 1980s, the major source for rubies was Thailand.
Vietnamese rubies originate in marble
In ancient Sanskrit, ruby is called ratnaraj or king of precious stones
Newly discovered ruby deposits at Vatomandry and Andilamena are in what country? Madagascar
Rubies from Pailin, Cambodia, are similar to those from Thailand
Corundum can form only in an environment that’s low in silicon
Where are the Penny Lane and John Saul mines located? Kenya
Heat-treating Mong Hsu rubies eliminates dark centers or cores
What location has supplied the world with most commercial-quality rubies since 1991? Mong Hsu
Switzerland exports rubies that are primarily high end
The most valuable tone and saturation for ruby are medium to medium-dark tone and vivid saturation
Kashmir’s most important sapphire production period was from 1881 to 1887
Blue sapphire’s most common crystal habit is a spindle-shaped hexagonal pyramid or bipyramid
The most highly valued hues of blue sapphire are blue to violetish blue
What trace elements cause blue sapphire’s color? Titanium and iron
When did Madagascar become a significant source of blue sapphire? 1990s
Milky, grayish, or brownish corundum that can be treated to a fine blue color is called geuda
Blue sapphire’s pleochroic colors are typically slightly greenish blue and slightly violetish blue
Most fine sapphires over 100 cts. come from Sri Lanka
Finer-quality Kashmir blue sapphires typically show velvety appearance
Of these characteristics, which one is most commonly seen in sapphire? A. Color zoning B. Etch tunnels C. Horsetail inclusions D. Three-phase inclusions Color zoning
Australian blue sapphire color is often described as inky
Which of the following sources emerged in the 1990’s as a significant source of good- to fine-quality sapphire? A. Kashmir B. Australia C. Sri Lanka D. Madagascar Madagascar
The sapphire market level supplied by Switzerland is upper
Which location supplies sapphires that are most likely not heat-treated? Yogo Gulch
Blue sapphires that originate in basaltic rock generally have high iron content
Asterism in black star sapphire is caused by hematite
Green sapphire is readily available
Which color of star sapphire is usually cut shallow due to parting? Black
A major source of black star sapphire is Australia
Which is the most prized body color in star corundum? Red
The first flame-fusion star rubies were produced in the 1940s
Which fancy sapphire hue regularly commands top prices? Pink
The best-quality star corundum is semi-transparent
What’s a common trade name for intensely saturated, light to medium pinkish orange to orange-pink sapphires? Padparadscha
Sapphire’s color change is caused by vanadium
Color-change sapphire typically changes from blue or violet to reddish purple
Fancy sapphires from Montana tend to be light in tone
What causes the pink color of corundum? Chromium
The most common number of rays in star corundum is 6 rays
The name padparadscha means lotus flower
The most desirable emerald hues are bluish green to green
Which two countries account for about 75 percent of emerald purchases worldwide? US and Japan
Who produced a hydrothermal synthetic emerald layer over faceted beryl seeds in the 1960s? Lechleitner
To emphasize the bluish green color, cutters orient a fashioned emerald with its table perpendicular to the crystal length.
Brazilian emeralds are mined from pegmatites, where they intersect with schists
The four major emerald sources are Colombia, Zambia, Brazil, and Zimbabwe
Compared to emeralds from other sources, emeralds from African mines generally contain fewer fractures
What’s the estimated percentage of fashioned emeralds that contain filled fractures? 90 or more
Which element makes emerald a bluer green? Iron
The trade term “Zambian” describes emeralds with more bluish color and darker tone than “Colombian.”
One of Colombia’s traditional emerald mines is called Coscuez
Emeralds were discovered in Zambia in the 1930s
The Sandawana emerald mine was discovered in the 1950s
Trapiche emeralds were first discovered in Muzo
Seed pearls are very small natural pearls
The nacreous layer inside a pearl-bearing mollusk’s shell is called mother-of-pearl
Pearl is an organic gem
A number of similar cultured pearl strands bundled together is called a hank
In the early 1990s, oysters in many important Japanese cultured pearl farming areas began to die off in massive numbers
The oyster used to grow Tahitian cultured pearls is Pinctada margaritifera
The first South Sea cultured pearl farm was founded in which country? Australia
By what date had Kokichi Mikimoto begun culturing whole pearls? 1908
Which industry directly contributed to the decline of the natural pearl industry? Oil
The four major types of cultured whole pearls are akoya, South Sea, freshwater, and Tahitian.
Saltwater whole cultured pearls grow from a mantle-tissue piece and a bead nucleus
South Sea cultured pearls are produced principally in Australia, Indonesia, and the Philippines
Aragonite is a crystallized form of calcium carbonate
The great majority of freshwater whole cultured pearls grow from a mantle-tissue piece only
Which country produces the most freshwater cultured pearls? China
The matching level that describes a group of pearls that have minor variations in uniformity is Good
Essence d’orient is a mixture of fish scales and varnish
Farmers of every cultured pearl type do at least which of these after harvest? Wash, dry, and sort
Usually, the diameters of the cultured pearls in a hank vary from each other by no more than 0.5 mm
Pearls that show noticeable surface characteristics are Moderately Blemished
Which overtone color increases the value of akoya cultured pearls with white bodycolor? Rosé
What happens when saltwater cultured pearls are exposed to gamma rays? Bead nucleus darkens
The nacre quality classification described as “Nucleus not noticeable, no chalky appearance” is Acceptable
The best way to clean pearls is with warm, mild soapy water
When mollusks live in cooler water, they form pearls with higher luster
In pearl culturing, the most difficult shape to produce is round
Pearl colors are low in saturation
Almost all akoya and Chinese freshwater pearls are bleached
The largest gem-quality natural pearl known is the Dudley
In the trade, Tahitian cultured pearls with a dark green-gray to blue-gray bodycolor and rosé to purple overtones are called peacock
In Myanmar, the center of the jadeite mining district is Hpakan
The most valuable level of transparency in jadeite is semitransparent
Polar jade is actually a very fine-quality fine green nephrite
Spinach jade is used to describe a color of dark green nephrite
Jadeite’s finest green color is caused by chromium
The finest texture category of jadeite is known as old mine
Spots of color near the surface of a jadeite boulder, where the skin is thin enough to see through, are called show points
New Zealand is a major source of nephrite
Where was jadeite first fashioned and used as an ornamental object? Central America as early as 1500 BC
Type B jadeite is bleached and impregnated jadeite
The toughness of jadeite is exceptional
The finest-quality jadeite is called Imperial
Guatemala recently emerged as a valuable source of which of the following jadeite colors? Black
Heat treatment of jadeite might produce orange color
Type C jadeite is dyed jadeite
Opal is composed primarily of silica
What is the transparency of gray-base black opal? Opaque
What is the first step in evaluating an opal? Determine its type
In opal, a pattern of large, distinct, usually rectangular patches of play-of-color with edges that touch each other is called harlequin
Most opal contains 3 to 10 percent water
Most opal formed 15 to 30 million years ago
The type of matrix found as a layer in finished boulder opal is ironstone
Which treatment involves immersing opal in concentrated sulfuric acid? Sugar
Experts think fire opal’s background color is caused by Iron impurities
Who created the first marketable synthetic opal? Pierre Gilson
Play-of-color that’s seen only when light travels through an opal to the eye is called Contra luz
Plastic imitation opal was first marketed in the late 1980s in Japan
What is the transparency range of white opal? Translucent to opaque
What is semi-black opal’s background color? Grayish
The first black opals were discovered in New South Wales
The color of chrysoprase is yellowish green
One of amethyst’s finest colors is medium-dark strong reddish purple
Chalcedony with curved or angular bands or layers that differ in color and transparency is known as Agate
Most of the citrine in the market is produced by heating amethyst
The source of natural ametrine is Bolivia
The major commercial-quality amethyst source is Brazil
Which of the following has the smallest crystal size? Cryptocrystalline aggregates
Tiger’s-eye quartz is a microcrystalline aggregate
The trade term “black onyx” is used for treated black chalcedony
“Marabá” amethyst is often uniform in color
Cryptocrystalline quartz is known as Chalcedony
In the nineteenth century, a major source of amethyst was discovered in Brazil
The color of amethyst results from color centers acting on iron
Which of the following gems has chatoyancy that’s caused by multiple slender crystals or channels? Cat’s-eye quartz
Dark amethyst is lightened by heating
Almost all tanzanite is heat-treated
What color is top-quality alexandrite in daylight? Bluish green
The most-prized chatoyant gem in the world is cat’s-eye chrysoberyl
Top-color iolite is untreated
Alexandrite was discovered in 1830
Untreated tanzanite is typically brownish
Tanavyte is a trade name for purple synthetic YAG
Where was tanzanite discovered? Merelani
In iolite, the most valuable main face-up color is blue
Which of the following gems is the most economically important? Tanzanite
The color change in alexandrite is caused by chromium
The name tanzanite was given to transparent blue zoisite by Tiffany & Co
What changes during alexandrite’s color-change effect? Hue
Tanzanite’s best color is strongly saturated blue or violetish blue
Which of the following is a major source of cat’s-eye chrysoberyl? Sri Lanka
What is the most common color of untreated, natural topaz? Colorless
The color of imperial topaz is reddish orange to orange-red
Most aquamarine has its color improved by heat
The term precious topaz is used for yellow-to-orange stones
The major source of imperial topaz is Ouro Prêto, Brazil
The finest aquamarine color is moderately strong, medium-dark blue to slightly greenish blue
Most gem-quality topaz comes from pegmatites
Which of the following is the rarest beryl? Red beryl
Which recent source is the leading producer of small, commercial-quality aquamarine? China
What color is morganite beryl? Pink
Which method is used to produce synthetic aquamarine? Hydrothermal
The most important source of aquamarine is Brazil
In order to attain a treated pink color, yellow to reddish brown topaz must contain chromium
The most valuable topaz varieties are pink and red
The only source of red beryl is in Utah
The most expensive variety of tourmaline is Paraíba
Many green and blue tourmalines are lightened by heating
Which of the following is the largest producer of chrome tourmaline? Tanzania
Paraíba tourmaline is colored by Copper
Which of the following trade terms is used for blue tourmaline? Indicolite
The world’s largest producer of gem-quality tourmaline is Brazil
Metamict zircons are described as low zircons due to their lower properties
Which countries produce the finest peridot? Myanmar
Most gem tourmalines form in pegmatites
The color of blue zircon is usually due to heat treatment
The cause of color in peridot is Iron
Most of the world’s commercial-quality peridot is mined in Arizona
Many Paraíba tourmalines are heated
Rubellite tourmaline is colored by Manganese
Tsavorite and hessonite are both varieties of grossularite
Which of the following has the widest color range? Grossularite than rhodolite, almandite, and spessartite
Demantoid was first discovered in Russia during the 1800s
Rhodolite is a mixture of mixture of almandite and pyrope
Spessartite is most commonly found in pegmatite veins
The most valuable spinel color is Red
Horsetail inclusions are found in demantoid
The trade term malaya is used for a pinkish orange garnet that’s a mixture of pyrope, spessartite, and almandite
The most important source of rhodolite in recent years is East Africa
Mandarin garnet has been used as a trade name for vibrant orange spessartite
Tsavorite is colored by Vanadium
The most desirable, vibrant, and rare blue natural spinels are colored by Cobalt and iron
All garnets have essentially the same crystal structure ~All garnets belong to the cubic crystal system
The substitution of one chemical element for another in the crystal structure of a mineral is called isomorphous replacement
The intense red color of spinel is caused by Chromium
Malachite’s color is caused by Copper
The only commercial source of charoite is Russia
A new turquoise treatment that appeared in the 1980s and has been used to treat more than 10 million carats is The Zachery method
The lapis lazuli trade grade that’s often spotted with green and shows obvious calcite is Chilean
Reconstructed turquoise is imitation turquoise
What is the color of the markings that sandstone matrix creates in turquoise? Tan
Stabilized turquoise is a trade term for Polymer-impregnated turquoise
The finest trade grade of lapis lazuli is Afghan
The purest blue colors of turquoise are caused by Copper
The finest color of turquoise is an even, intense medium blue
The major source of turquoise today is southwestern US
The major source for top-color turquoise today is China
The world’s major source of lapis lazuli is Afghanistan
Which of the following does turquoise usually form in? limonite or sandstone
The trade term for top-color turquoise is Persian
The adularescence of the finest moonstones is Blue
Kunzite’s most common color is Light pink
Tiny tension cracks in moonstone are called centipedes
Light-colored or colorless spodumene can be treated to a kunzite color by irradiation followed by careful heating
An intense, unstable green color can be created in spodumene by Irradiation
How many cleavage directions are found in feldspar, spodumene, and diopside? Two
Moonstone is a variety of orthoclase
The greenish blue feldspar that has gridlike white streaks and resembles turquoise is Amazonite
Spectrolite is a variety of labradorite
What color is hiddenite? Medium green
The color of chrome diopside is natural
Rainbow moonstone is a trade term for a type of labradorite
Which of the following is a commercial source of chrome diopside? Russia
Which of the following three basic chemical elements do all feldspars contain? Aluminum, oxygen, and silicon
In which era did moonstone go out of style? Art Deco
Jet is an ornamental form of lignite coal
Immature amber is known as Copal
Which animal’s tusk produces the most valuable ivory? Elephant
Amber is actually hardened tree resin
The only source of gem-quality benitoite is San Benito County, California
Which of the following is a calcium carbonate? Pink coral
Paua is a Maori name for abalone shell
Which of the following gems is a natural glass? Moldavite
Which treatment can create a golden color from black coral? Bleaching
Which of the following organics shows a structure called “engine turning,” which looks like lines created on a lathe? Ivory
The amber color that’s most valuable is Red
The major source of jet is England
Coral’s most valuable color is red
Which of the following is a variety of conchiolin coral? Black
Tortoise shell is composed of protein
Created by: gpamies