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90 Cards in this Set
- Front
- Back
A gem produced by, or derived from, a living organism is
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organic
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Which of the following is an organic gem?
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amber
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A Substance that consists of atoms of only one kind is a?
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chemical element
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A natural, inorganic substance with a characteristic chemical composition and usually characteristic crystal structure?
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mineral
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Most gems are?
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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?
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rock
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Which of the following is amorphous?
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amber
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A broad gem category based on chemical composition and crystal structure is a?
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gem species
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Which of the following is a gem variety?
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demantoid
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Which group does almandite belong to?
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garnet
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The world's larges gem consuming market is?
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united states
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Compared to the US domestic market for diamonds, the us domestic market for natural, unset, non diamond gems is?
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less than a tenth of the size
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To be a gem, a mineral must be beautiful, durable, and?
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rare
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Many colored stones are mined by?
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independent miners using small scale mining methods
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Media attention in the 1990's regarding its treatment reduced consumer confidence in?
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emerald
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Most gems form in the?
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continental crust
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rocks altered by heat and pressure are?
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metamorphic
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Which gem can crystallize in volcanic rock from gasses released by magma?
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red beryl
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Which is a key locality for hydrothermal gems?
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ouro preto, brazil
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Which gem forms by metamorphism?
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tanzanite
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Heat and pressure transform limestone into?
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marble
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A deposit where gems are found in the rock that carried them to the earth's surface is called?
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primary
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Which type of deposit is usually the most profitable for colored stone mining?
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secondary
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Which is a deposit where gems eroded from the source rock and remained in a place nearby?
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eluvial
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Which is a workable alluvial deposit of gem minerals with economic potential?
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placer
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Kunzite is most often found in association with?
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tourmaline and beryl in pegmatite
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Myanmar's famous Mogok ruby deposits were formed by?
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regional metamorphism
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Pegmatite gems are rich in volatile elements like?
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beryllium, boron, and lithium
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Most of the gems in Tanzania's Umba River Valley are found in?
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place deposits
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Emeralds are rarely found in place deposits because they're?
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unable to withstand much abrasion
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A unit cell deines a mineral's?
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basic identity
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If a crystal grows in a flux that is highly saturated with the necessary elements, it tends to be?
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small
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Which aggregate's crystals are visible only with magnification greater than a standard gemological microscope's?
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cryptocrystalline
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Which is classified in the orthorhombic crystal system?
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topaz
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Which element causes red in ruby and green in emerald?
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chromium
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Which type of twinning is caused by environmental change after the gem forms?
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polysynthetic
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Wich type of twinning looks as if two crystal halves are mirror images?
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contact
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Needles of actinolite found in emerald are classified as
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inclusions
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A two-phase inclusion is a cavity in a gem that's typically filled with a?
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liquid and a gas
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Atoms in a gem that are not part of its essential chemical composition are?
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trace elements
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The trace elements that cause corundum's blue are?
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iron and titanium
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An object's weight in relation to its size is called its?
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density
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Which gems are cryptocrystalline aggregates?
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chalcedony and turquoise
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Rough spinel often occurs as?
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twinned crystals
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Many fashioned rubies have shallow proportions because they're cut from?
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flat crystals
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The pattern of dark lines or bands shown by certain colored gems when viewed through a spectroscope is called?
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absorption spectrum
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Which element does chromium substitute for to cuase ruby's red?
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aluminum
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A gem colored by an element that's part of its basic chemistry is called?
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idiochromatic
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Which element causes the color of both almandite and peridot?
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iron
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The process where electrons that selectively absorb light are passed back and forth between neighboring impurity ions is known as?
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charge transfer
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Which components of a transition element's atoms can produce color in gems?
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electrons
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Which element cuases the finest reds and greens in gemstones?
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chromium
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Which transition element causes more different colors in gems than any other?
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iron
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In many blue sapphires, the intervalence charge transfer that causes the color is between?
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iron and titanium
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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?
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double refraction
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What is the only type of gem that can show pleochroism?
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doubly refractive
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Which gem can show three pleochroic colors?
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iolite
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Which phenomenon is a broad color flash?
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labradorescence
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Adularescence is caused by?
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scattering of light
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The best known and most valuable chatoyant gem is cat's eye?
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chrysoberyl
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A laboratory created gem with essentially the same chemical composition, crystal structure, and properties as its natural counterpart?
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synthetic
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Two main types of processes for synthetic gem production are melt and?
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solution
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Low cost and high volume characterize which process?
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flame fusion
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What synthetic process developed rapidly due to laser research in the 1960's?
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pulling
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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?
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floating zone
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Which process dissolves nutrients in chemicals to form synthetic?
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flux
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The crucibles that work best for flux growth are made of?
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platinum
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The hydrothermal growth process is the only method used to produce which synthetic gem?
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quartz
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Which synthetic process usses an autoclave?
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hydrothermal growth
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Synthetic opal is grown using microscopic silica spheres that are produced by?
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precipitation
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Which process involves heating finely ground powder, sometimes under pressure, to produce a fine-grained solid material?
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ceramic
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Synthetic turquoise is most likely produced by which process?
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ceramic
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The flux used in the flux process is a solid material that, when molten?
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dissolves other materials
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The hydrothermal synthetic process requires a?
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pressurized steel container and cruhed chemical ingredients
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A snakeskin structural pattern is typical of?
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synthetic opal
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Which is considered a gem treatment?
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fracture filling
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Written information on dyeing gems dates back to about?
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200 bc
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Which is commonly heat treated?
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amber
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Heat can lighten amethyst's purple by?
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causing changes in color centers
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Creating asterism with heat treatment is most common in?
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synthetic corundum
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What coloring agents do treaters use during surface diffusion to create a shallow layer of blue color in corundum?
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titanium oxide and iron oxide
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How deep is the color layer that surface diffusion creates in corundum?
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0.01 mm to 0.50 mm
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What agent can treaters intorduce below the surface of a corundum cabochon during surface diffusion to create a shallow layer of asterism?
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titanium oxide
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For effective clarity enhancement, the material used to fill a gem's fractures must have nearly the same?
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refractive index as the gem
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After irradiation, which gem's color is stable under normal wearing conditions?
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golden beryl
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Jadeite is often?
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bleached an polymer impregnated
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The Zachery method is a treatment applied to?
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turquoise
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Heat treatment in a reducing environment?
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deepens blue color in sapphire
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Quartz or topaz with a thin layer of gold deposited on the surface is known as?
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Aqua aura
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Treaters use sugar treatment to enhance?
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opal
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