GIA Colored Stone Final Exam QUESTIONS
WITH COMPLETE SOLUTIONS 2024/2025
By what date had Kokichi Mikimoto begun culturing whole pearls
1908
Synthetic gem materials
Are not minerals
which of the following is an organic gem
amber
which of the following is amorphous
amber
a natural material that's made up of a mass of one or more kinds of mineral crystals is
rock
what group does alamandine belong to
garnet
A gem produced by, or derived from, a living organism is
organic
which of the following is a gem variety
demantoid
the world's largest gem-consuming market is
the US
a substance that consists of atoms of only one kind is a
chemical element
Media attention in the 1990s regarding its treatment reduced consumer confidence in
emerald
a natural, inorganic substance with a characteristic chemical composition and usual crystal
structure is a
mineral
most gems are
minerals
To be a gem, a mineral must be beautiful, durable, and
rare
a broad gem category based on chemical composition and crystal structure is called a
gem species
,Many colored stones are mined by
independent miners using small-scale mining methods.
Rocks altered by heat and pressure beneath Earth's surface are
metamorphic
Which type of deposit is usually the most profitable for colored stone mining?
secondary
Which gem can crystallize in volcanic rock from gasses released by magma?
red beryl
Emeralds are rarely found in placer deposits because they're
unable to withstand much abrasion
Which is a workable alluvial deposit of gem minerals with economic potential?
placers
Which is a deposit where gems eroded from the source rock and remained in place nearby?
eluvial
from granite, pegmatite gems get exotic elements like
beryllium, boron, and lithium
Myanmar's famous Mogok ruby deposits were formed by
metamorphic process
most of the gems in tanzania's umba river valley are formed in
placer deposits
A deposit where gems are found in the rock that where they formed is called
primary deposit
Which is a key locality for hydrothermal gems?
Ouro Preto, Brazil
Heat and pressure transform limestone into
marble
which gem form by metamophosis
tanzanite
Most gemstones form in the
continental crust
kunzite is most often associated with
tourmaline and beryl in pegmatites
how heavy an object is in relation to its size
density
A two-phase inclusion is a cavity in a gem that's typically filled with a
liquid and a gas
which type of twinning is caused by environmental change after a gem forms
, polysynthetic
which element caused red in ruby and green in emerald
chromium
A unit cell defines a mineral's
basic identity
which type of twinning looks as if two crystal halves are mirror images
contact twinning
crystals that grow in a flux that is highly saturated with the necessary elements tend to be -
small
which is classified in the orthorhombic crystal system
topaz
Which gems are cryptocrystalline aggregates?
Chalcedony and turquoise
Atoms in a gem that aren't part of its essential chemical composition are called
trace elements
Many fashioned rubies have shallow proportions because they're cut from
flattened crystals
Rough spinel often occurs as
twinned crystals
Needles of actinolite found in emerald are classified as
inclusions
which aggregates crystals are visible only under very high magnification
cryptocrystalline
the trace elements that cause corundum's blue are
iron and titanium
what element does chromium substitute for to cause ruby's red
aluminium
In many blue sapphires, the intervalence charge transfer that causes the color is between
iron and titanium
The pattern of dark vertical lines or bands shown by certain gems when viewed through a
spectroscope is called
absorption spectrum
the process where electrons that selectively absorb light are passed back and forth between
neighboring impurity ions is known as
charge transfer
what element causes the color of both alamandine and peridot
iron
WITH COMPLETE SOLUTIONS 2024/2025
By what date had Kokichi Mikimoto begun culturing whole pearls
1908
Synthetic gem materials
Are not minerals
which of the following is an organic gem
amber
which of the following is amorphous
amber
a natural material that's made up of a mass of one or more kinds of mineral crystals is
rock
what group does alamandine belong to
garnet
A gem produced by, or derived from, a living organism is
organic
which of the following is a gem variety
demantoid
the world's largest gem-consuming market is
the US
a substance that consists of atoms of only one kind is a
chemical element
Media attention in the 1990s regarding its treatment reduced consumer confidence in
emerald
a natural, inorganic substance with a characteristic chemical composition and usual crystal
structure is a
mineral
most gems are
minerals
To be a gem, a mineral must be beautiful, durable, and
rare
a broad gem category based on chemical composition and crystal structure is called a
gem species
,Many colored stones are mined by
independent miners using small-scale mining methods.
Rocks altered by heat and pressure beneath Earth's surface are
metamorphic
Which type of deposit is usually the most profitable for colored stone mining?
secondary
Which gem can crystallize in volcanic rock from gasses released by magma?
red beryl
Emeralds are rarely found in placer deposits because they're
unable to withstand much abrasion
Which is a workable alluvial deposit of gem minerals with economic potential?
placers
Which is a deposit where gems eroded from the source rock and remained in place nearby?
eluvial
from granite, pegmatite gems get exotic elements like
beryllium, boron, and lithium
Myanmar's famous Mogok ruby deposits were formed by
metamorphic process
most of the gems in tanzania's umba river valley are formed in
placer deposits
A deposit where gems are found in the rock that where they formed is called
primary deposit
Which is a key locality for hydrothermal gems?
Ouro Preto, Brazil
Heat and pressure transform limestone into
marble
which gem form by metamophosis
tanzanite
Most gemstones form in the
continental crust
kunzite is most often associated with
tourmaline and beryl in pegmatites
how heavy an object is in relation to its size
density
A two-phase inclusion is a cavity in a gem that's typically filled with a
liquid and a gas
which type of twinning is caused by environmental change after a gem forms
, polysynthetic
which element caused red in ruby and green in emerald
chromium
A unit cell defines a mineral's
basic identity
which type of twinning looks as if two crystal halves are mirror images
contact twinning
crystals that grow in a flux that is highly saturated with the necessary elements tend to be -
small
which is classified in the orthorhombic crystal system
topaz
Which gems are cryptocrystalline aggregates?
Chalcedony and turquoise
Atoms in a gem that aren't part of its essential chemical composition are called
trace elements
Many fashioned rubies have shallow proportions because they're cut from
flattened crystals
Rough spinel often occurs as
twinned crystals
Needles of actinolite found in emerald are classified as
inclusions
which aggregates crystals are visible only under very high magnification
cryptocrystalline
the trace elements that cause corundum's blue are
iron and titanium
what element does chromium substitute for to cause ruby's red
aluminium
In many blue sapphires, the intervalence charge transfer that causes the color is between
iron and titanium
The pattern of dark vertical lines or bands shown by certain gems when viewed through a
spectroscope is called
absorption spectrum
the process where electrons that selectively absorb light are passed back and forth between
neighboring impurity ions is known as
charge transfer
what element causes the color of both alamandine and peridot
iron
