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GIA Colored Stones
| Question | Answer |
|---|---|
| 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 |
| 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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gpamies
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