GIA Colored Stones
Quiz yourself by thinking what should be in
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| A natural inorganic substance with a characteristic chemical composition and usually characteristic crystal structure is a | Mineral
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| A substance that consists of atoms of only one kind is a | chemical element
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| Most gems are | minerals
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| A natural material that’s made up of a mass of one or more kinds of mineral crystals is a | rock
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| Which of the following is amorphous? A. Beryl B. Amber C. Garnet D. Jadeite | B. Amber
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| A broad gem category based on chemical composition and crystal structure is a | gem species
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| Which of the following is a gem variety? A. Beryl B. Garnet C. Andradite D. Demantoid | Demantoid
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| Which group does almandine belong to? | Garnet
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| The world’s largest gem-consuming market is | United States
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| Synthetic gem materials | are not minerals
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| Many colored stones are mined by | independent miners using small-scale mining methods
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| Media attention in the 1990s regarding its treatment reduced consumer confidence in | emerald
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| Most of the gems in Tanzania’s Umba River Valley are found in | placer deposits
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| Which is a key locality for hydrothermal gems? | Ouro Preto, Brazil
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| Which gem can crystallize in volcanic rock from gasses released by magma? | Red beryl
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| A deposit where gems are found in the rock that carried them to the earth’s surface is called | primary
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| Which type of deposit is usually the most profitable for colored stone mining? | Secondary
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| Which gem forms by metamorphism? | Tanzanite
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| Most gemstones form in the | continental crust
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| Which is a workable alluvial deposit of gem minerals with economic potential? | Placer
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| Pegmatite gems are rich in volatile elements like | beryllium, boron, and lithium
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| Heat and pressure transform limestone into | marble
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| Kunzite is most often found in association with | Tourmaline, beryl, and kunzite are all found in association with pegmatites
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| Emeralds are rarely found in placer deposits because they’re | too delicate to withstand abrasion
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| Rocks altered by heat and pressure are | metamorphic
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| Which is a deposit where gems eroded from the source rock and remained in place nearby? | Eluvial
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| Myanmar’s famous Mogok ruby deposits were formed by | regional metamorphism
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| The trace elements that cause corundum’s blue are | iron and titanium
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| Atoms in a gem that are not part of its essential chemical composition are | trace elements
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| Many fashioned rubies have shallow proportions because they’re cut from | flat crystals
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| A two-phase inclusion is a cavity in a gem that’s typically filled with a | liquid and a gas
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| Rough spinel often occurs as | twinned crystals
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| Needles of actinolite found in emerald are classified as | inclusions
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| Which type of twinning is caused by environmental change after the gem forms? | Polysynthetic
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| Which gems are cryptocrystalline aggregates? | Chalcedony and turquoise
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| Which element causes red in ruby and green in emerald? | Chromium
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| Which aggregate’s crystals are visible only with magnification greater than a standard gemological microscope’s? | Cryptocrystalline
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| If a crystal grows in a flux that is highly saturated with the necessary elements, it tends to be | small
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| An object’s weight in relation to its size is called its | density
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| A unit cell defines a mineral’s | basic identity
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| Which is classified in the orthorhombic crystal system? | topaz
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| Which type of twinning looks as if two crystal halves are mirror images? | contact twins
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| The pattern of dark lines or bands shown by certain colored gems when viewed through a spectroscope is called | absorption spectrum
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| Which element does chromium substitute for to cause ruby’s red? | Aluminum
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| Which element causes the color of both almandite and peridot? | Iron
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| In many blue sapphires, the intervalence charge transfer that causes the color is between | iron and titanium
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| What is the only type of gem that can show pleochroism? | Doubly refractive
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| Which components of a transition element’s atoms can produce color in gems? | Electrons
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| Which phenomenon is a broad color flash? | Labradorescence
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| Adularescence is caused by | scattering of light
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| Which gem can show three pleochroic colors? | iolite
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| The process where electrons that selectively absorb light are passed back and forth between neighboring impurity ions is known as... | charge transfer
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| Which element causes the finest reds and greens in gemstones? | Chromium
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| Which transition element causes a greater variety of gem colors than any other? | Iron
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| The best-known and most valuable chatoyant gem is cat’s-eye | chrysoberyl
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| 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
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| A gem colored by an element that’s part of its basic chemistry is called | IDIOCHROMATIC
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| Synthetic opal is grown using microscopic silica spheres that are produced by | precipitation
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| A snakeskin structural pattern is typical of | synthetic opal
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| Synthetic turquoise is most likely produced by which process? | Ceramic
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| Which synthetic process uses an autoclave? | Hydrothermal growth
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| The hydrothermal synthetic process requires a | pressurized steel container and crushed chemical ingredients
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| Which process dissolves nutrients in chemicals to form synthetic crystals? | Flux growth
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| The two main types of processes for synthetic gem production are melt and | solution
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| Low cost and high volume characterize which process? | Flame fusion
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| Which process involves heating finely ground powder, sometimes under pressure, to produce a fine-grained solid material? | Ceramic
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| A laboratory-created gem with essentially the same chemical composition, crystal structure, and properties as its natural counterpart is a | synthetic
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| Which synthetic process developed rapidly due to laser research in the 1960s? | Pulling
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| The hydrothermal growth process is the only method used to produce which synthetic gem? | Quartz
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| The crucibles that work best for flux growth are made of | platinum
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| Which process uses a heating unit to pass over a rotating solid rod of chemicals until it forms a synthetic crystal? | Floating zone
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| The flux used in the flux process is a solid material that when molten | dissolves other materials
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| Heat can lighten amethyst’s purple by | causing changes in color centers
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| Heat treatment in a reducing environment | deepens blue color in sapphire
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| Which of these is considered a gem treatment? | Fracture filling
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| Written information on dyeing gems dates back to about | 200 bc
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| Creating asterism with heat treatment is most common in | synthetic corundum
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| 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
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| Jadeite is often | bleached and polymer impregnated
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| For effective clarity enhancement, the material used to fill a gem’s fractures must have nearly the same | refractive index as the gem
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| The Zachery Method is a treatment applied to | turquoise
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| What coloring agents do treaters use during lattice diffusion to create a shallow layer of blue color in corundum? | Titanium oxide and iron oxide
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| Treaters use sugar treatment to enhance | opal
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| Which gem is commonly heat-treated? | Amber
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| After irradiation, which gem’s color is stable under normal wearing conditions? | Golden beryl
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| How deep is the color layer that lattice diffusion with titanium or chromium creates in corundum? | 0.01 mm to 0.50 mm
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| Quartz or topaz with a thin layer of gold deposited on the surface is known as | aqua aura
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| Which location produces the majority of rubies that end up in mass-produced jewelry? | Mong Hsu
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| Which trade term describes a mixture of gem qualities that represents unsorted production from a particular mine? | Mine run
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| 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
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| Which term describes a random sample from a parcel of gemstones, often used to assess the parcel’s overall quality? | pick
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| Which term describes a specific rough gemstone quality range, usually determined by color, size, clarity, and price? | grade
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| Which of these is a cutting center for colored stones in Thailand? A. Pailin B. Mogok C. Mong Hsu D. Chantaburi | Chantaburi
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| Materials cut free-size are usually | large, important stones
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| Where is rough from Mong Hsu brought into Thailand? | Mae Sai
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| 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
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| Gemstone sizes cut to fit standard mountings are known as | calibrated sizes
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| Where is rough from Mogok brought into Thailand? | Mae Sot
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| In mining terms, the theft of a mine’s production by its workers is known as | high grading
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| 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
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| The market sector where better-quality gemstones are used in well-finished, moderately priced jewelry is known as the | middle market
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| What is Myanmar’s most important gem export? | Ruby
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| The first impression of an object’s basic color is its | HUE
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| Emission of visible light by a material when it’s exposed to invisible ultraviolet radiation is | fluorescence
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| Use trade terms that imply geographic origin only if the | gem’s actual source is known
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| A see-through area in a transparent gemstone’s bodycolor that usually results from the way the gem was cut is called | a window
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| Higher levels of saturation are usually found in stones with | medium to medium-dark tone
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| What type of lighting is best for grading color in a colored stone? | Daylight-equivalent fluorescent
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| Which trade term describes certain tourmalines? | Paraíba
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| Which gemstone occurs in almost every color? | Tourmaline
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| Extinction results from | deep pavilions
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| Which abbreviation does the GIA Colored Stone Grading System use for a slightly purplish red hue? | slpR
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| In practice, what GIA Colored Stone Grading tone levels apply to grading transparent colored stones? | 2 through 8
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| Generally, cool-colored hues with low saturation look | grayish
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| A window usually differs from the rest of the stone in | saturation
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| What two coloring agents are usually responsible for color change in gemstones? | Chromium and vanadium
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| The color of the background for grading a colored stone should be | neutral
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| Which type of rough is usually faceted? | Transparent
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| Removing heavily included sections from gemstone rough by carefully tapping it with a small hammer is known as | cobbing
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| Which is a carved design that projects slightly from a flat or curved surface? | Cameo
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| Which cutting stage has the greatest impact on the value of the finished gem? | Preforming
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| To judge brilliance, view the stone | face-up
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| The purpose of most variations in a colored stone’s face-up outline is to | save weight
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| Colored stones that rate “fair” for brilliance have | between 25 and 40 percent brilliance
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| Which is most likely to undergo cobbing? | Commercial-quality amethyst rough
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| Excessive bulge on a step cut | adds weight
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| Rough that’s ground to the approximate shape of the finished stone is called | preform
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| Colored stones cut flat with shallow pavilions usually have areas of lower color intensity called | windows
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| To retain as much weight as possible from rare, high-quality rough, cutters would most likely vary | proportions
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| Which colored stone variety has cutting challenges due to vulnerable cleavage planes? | Tanzanite
(Tanzanite has two directions of cleavage)
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| Translucent to opaque rough is often cut into a | cabochon
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| Cutters can darken the color of pale stones by cutting a | deep pavilion
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| In which colored stone clarity type are the gems usually eye-clean? | Type I
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| Inclusions are important to gemologists because they | can help separate natural from synthetic gems
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| Fingerprints are | partially healed fracture planes
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| The term “silk” describes | a group of fine, needle-like inclusions
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| An inclusion with the most negative impact on a colored stone’s clarity would be located | under the table
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| A general term for a break in a stone is | feather
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| 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
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| An angular, hollow space that resembles a mineral inclusion is called a | negative crystal
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| Gems that are usually eye-clean include | spodumene, yellow beryl, and aquamarine
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| In which of the following colored stone clarity grades do the definitions vary for each clarity type? | Moderately included
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| Which of these gems is classified as Type III? A. Ruby B. Topaz C. Emerald D. Chrysoberyl | Emerald
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| The highest clarity grade for colored stones is | eye-clean
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| A characteristic or irregularity confined to the surface of a polished gemstone is a | blemish
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| Two factors that determine an inclusion’s impact on a gem’s value are | position and relief
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| Growth zoning in a colored stone is evidence of | crystal growth
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| 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)
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| Most colored stones are sold | by weight
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| A metric carat equals | 0.20 gram
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| The international unit of measurement for gem weight is the | metric carat
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| When you first start to count a large pile of small gems, it’s best to separate them into groups of | 5
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| What category of colored stone is often sold per piece? | Small, inexpensive
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| 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
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| Individual stone prices are referred to as | unit prices
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| Sieves are most useful for sorting round gems with diameters | 3 mm and below
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| 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)
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| A gem’s price divided by its carat weight is called | per-carat price
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| Colored stones with higher values usually have | medium to medium-dark tone and vivid saturation
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| The color of a sorting pad should be | neutral
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| 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
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| How many points are in a metric carat? | 100
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| Ruby deposits in Thailand and Cambodia are associated with | alkali-basalt
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| The world’s largest corundum marketing center is | Thailand.
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| Rubies that come from marble deposits are typically low in | iron
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| Compared to rubies from Myanmar, most Thai rubies tend to be | darker
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| In the early 1980s, the major source for rubies was | Thailand.
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| Vietnamese rubies originate in | marble
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| In ancient Sanskrit, ruby is called ratnaraj or | king of precious stones
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| Newly discovered ruby deposits at Vatomandry and Andilamena are in what country? | Madagascar
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| Rubies from Pailin, Cambodia, are similar to those from | Thailand
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| Corundum can form only in an environment that’s low in | silicon
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| Where are the Penny Lane and John Saul mines located? | Kenya
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| Heat-treating Mong Hsu rubies | eliminates dark centers or cores
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| What location has supplied the world with most commercial-quality rubies since 1991? | Mong Hsu
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| Switzerland exports rubies that are primarily | high end
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| The most valuable tone and saturation for ruby are | medium to medium-dark tone and vivid saturation
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| Kashmir’s most important sapphire production period was from | 1881 to 1887
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| Blue sapphire’s most common crystal habit is | a spindle-shaped hexagonal pyramid or bipyramid
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| The most highly valued hues of blue sapphire are | blue to violetish blue
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| What trace elements cause blue sapphire’s color? | Titanium and iron
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| When did Madagascar become a significant source of blue sapphire? | 1990s
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| Milky, grayish, or brownish corundum that can be treated to a fine blue color is called | geuda
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| Blue sapphire’s pleochroic colors are typically | slightly greenish blue and slightly violetish blue
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| Most fine sapphires over 100 cts. come from | Sri Lanka
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| Finer-quality Kashmir blue sapphires typically show | velvety appearance
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| 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
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| Australian blue sapphire color is often described as | inky
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| 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
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| The sapphire market level supplied by Switzerland is | upper
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| Which location supplies sapphires that are most likely not heat-treated? | Yogo Gulch
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| Blue sapphires that originate in basaltic rock generally have | high iron content
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| Asterism in black star sapphire is caused by | hematite
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| Green sapphire is | readily available
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| Which color of star sapphire is usually cut shallow due to parting? | Black
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| A major source of black star sapphire is | Australia
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| Which is the most prized body color in star corundum? | Red
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| The first flame-fusion star rubies were produced in the | 1940s
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| Which fancy sapphire hue regularly commands top prices? | Pink
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| The best-quality star corundum is | semi-transparent
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| What’s a common trade name for intensely saturated, light to medium pinkish orange to orange-pink sapphires? | Padparadscha
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| Sapphire’s color change is caused by | vanadium
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| Color-change sapphire typically changes from blue or violet to | reddish purple
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| Fancy sapphires from Montana tend to be | light in tone
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| What causes the pink color of corundum? | Chromium
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| The most common number of rays in star corundum is | 6 rays
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| The name padparadscha means | lotus flower
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| The most desirable emerald hues are | bluish green to green
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| Which two countries account for about 75 percent of emerald purchases worldwide? | US and Japan
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| Who produced a hydrothermal synthetic emerald layer over faceted beryl seeds in the 1960s? | Lechleitner
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| To emphasize the bluish green color, cutters orient a fashioned emerald with its table | perpendicular to the crystal length.
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| Brazilian emeralds are mined from | pegmatites, where they intersect with schists
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| The four major emerald sources are Colombia, Zambia, Brazil, and | Zimbabwe
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| Compared to emeralds from other sources, emeralds from African mines | generally contain fewer fractures
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| What’s the estimated percentage of fashioned emeralds that contain filled fractures? | 90 or more
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| Which element makes emerald a bluer green? | Iron
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| The trade term “Zambian” describes emeralds with | more bluish color and darker tone than “Colombian.”
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| One of Colombia’s traditional emerald mines is called | Coscuez
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| Emeralds were discovered in Zambia in the | 1930s
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| The Sandawana emerald mine was discovered in the | 1950s
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| Trapiche emeralds were first discovered in | Muzo
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| Seed pearls are | very small natural pearls
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| The nacreous layer inside a pearl-bearing mollusk’s shell is called | mother-of-pearl
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| Pearl is | an organic gem
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| A number of similar cultured pearl strands bundled together is called a | hank
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| In the early 1990s, oysters in many important Japanese cultured pearl farming areas began to | die off in massive numbers
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| The oyster used to grow Tahitian cultured pearls is | Pinctada margaritifera
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| The first South Sea cultured pearl farm was founded in which country? | Australia
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| By what date had Kokichi Mikimoto begun culturing whole pearls? | 1908
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| Which industry directly contributed to the decline of the natural pearl industry? | Oil
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| The four major types of cultured whole pearls are akoya, South Sea, freshwater, and | Tahitian.
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| Saltwater whole cultured pearls grow from a | mantle-tissue piece and a bead nucleus
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| South Sea cultured pearls are produced principally in Australia, Indonesia, and | the Philippines
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| Aragonite is a crystallized form of | calcium carbonate
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| The great majority of freshwater whole cultured pearls grow from a | mantle-tissue piece only
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| Which country produces the most freshwater cultured pearls? | China
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| The matching level that describes a group of pearls that have minor variations in uniformity is | Good
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|
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| Essence d’orient is a mixture of | fish scales and varnish
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|
||||
| Farmers of every cultured pearl type do at least which of these after harvest? | Wash, dry, and sort
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||||
| Usually, the diameters of the cultured pearls in a hank vary from each other by no more than | 0.5 mm
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|
||||
| Pearls that show noticeable surface characteristics are | Moderately Blemished
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|
||||
| Which overtone color increases the value of akoya cultured pearls with white bodycolor? | Rosé
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|
||||
| What happens when saltwater cultured pearls are exposed to gamma rays? | Bead nucleus darkens
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|
||||
| The nacre quality classification described as “Nucleus not noticeable, no chalky appearance” is | Acceptable
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|
||||
| The best way to clean pearls is with | warm, mild soapy water
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|
||||
| When mollusks live in cooler water, they form | pearls with higher luster
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|
||||
| In pearl culturing, the most difficult shape to produce is | round
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|
||||
| Pearl colors are | low in saturation
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|
||||
| Almost all akoya and Chinese freshwater pearls are | bleached
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|
||||
| The largest gem-quality natural pearl known is the | Dudley
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|
||||
| In the trade, Tahitian cultured pearls with a dark green-gray to blue-gray bodycolor and rosé to purple overtones are called | peacock
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|
||||
| In Myanmar, the center of the jadeite mining district is | Hpakan
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|
||||
| The most valuable level of transparency in jadeite is | semitransparent
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|
||||
| Polar jade is actually a very fine-quality | fine green nephrite
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|
||||
| Spinach jade is used to describe a color of | dark green nephrite
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|
||||
| Jadeite’s finest green color is caused by | chromium
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|
||||
| The finest texture category of jadeite is known as | old mine
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|
||||
| Spots of color near the surface of a jadeite boulder, where the skin is thin enough to see through, are called | show points
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|
||||
| New Zealand is a major source of | nephrite
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|
||||
| Where was jadeite first fashioned and used as an ornamental object? | Central America as early as 1500 BC
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|
||||
| Type B jadeite is | bleached and impregnated jadeite
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|
||||
| The toughness of jadeite is | exceptional
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|
||||
| The finest-quality jadeite is called | Imperial
🗑
|
||||
| Guatemala recently emerged as a valuable source of which of the following jadeite colors? | Black
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|
||||
| Heat treatment of jadeite might produce | orange color
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|
||||
| Type C jadeite is | dyed jadeite
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|
||||
| Opal is composed primarily of | silica
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|
||||
| What is the transparency of gray-base black opal? | Opaque
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|
||||
| What is the first step in evaluating an opal? | Determine its type
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|
||||
| In opal, a pattern of large, distinct, usually rectangular patches of play-of-color with edges that touch each other is called | harlequin
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|
||||
| Most opal contains | 3 to 10 percent water
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|
||||
| Most opal formed | 15 to 30 million years ago
🗑
|
||||
| The type of matrix found as a layer in finished boulder opal is | ironstone
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|
||||
| 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
🗑
|
||||
| elbaite
🗑
|
|||||
| 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
🗑
|
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