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90 Cards in this Set

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