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 |