GIA COLORED STONE EXAM 390 QUESTIONS &
CORRECT ANSWERS LATEST 2025
By what date had Kokichi Mikimoto begun culturing whole pearls - ANSWER-
1908
Synthetic gem materials - ANSWER-Are not minerals
which of the following is an organic gem - ANSWER-amber
which of the following is amorphous - ANSWER-amber
a natural material that's made up of a mass of one or more kinds of mineral crystals
is - ANSWER-rock
what group does alamandine belong to - ANSWER-garnet
A gem produced by, or derived from, a living organism is - ANSWER-organic
which of the following is a gem variety - ANSWER-demantoid
the world's largest gem-consuming market is - ANSWER-the US
a substance that consists of atoms of only one kind is a - ANSWER-chemical
element
,Media attention in the 1990s regarding its treatment reduced consumer confidence
in - ANSWER-emerald
a natural, inorganic substance with a characteristic chemical composition and usual
crystal structure is a - ANSWER-mineral
most gems are - ANSWER-minerals
To be a gem, a mineral must be beautiful, durable, and - ANSWER-rare
a broad gem category based on chemical composition and crystal structure is called
a - ANSWER-gem species
Many colored stones are mined by - ANSWER-independent miners using small-
scale mining methods.
Rocks altered by heat and pressure beneath Earth's surface are - ANSWER-
metamorphic
Which type of deposit is usually the most profitable for colored stone mining? -
ANSWER-secondary
Which gem can crystallize in volcanic rock from gasses released by magma? -
ANSWER-red beryl
Emeralds are rarely found in placer deposits because they're - ANSWER-unable to
withstand much abrasion
,Which is a workable alluvial deposit of gem minerals with economic potential? -
ANSWER-placers
Which is a deposit where gems eroded from the source rock and remained in place
nearby? - ANSWER-eluvial
from granite, pegmatite gems get exotic elements like - ANSWER-beryllium,
boron, and lithium
Myanmar's famous Mogok ruby deposits were formed by - ANSWER-
metamorphic process
most of the gems in tanzania's umba river valley are formed in - ANSWER-placer
deposits
A deposit where gems are found in the rock that where they formed is called -
ANSWER-primary deposit
Which is a key locality for hydrothermal gems? - ANSWER-Ouro Preto, Brazil
Heat and pressure transform limestone into - ANSWER-marble
which gem form by metamophosis - ANSWER-tanzanite
Most gemstones form in the - ANSWER-continental crust
, kunzite is most often associated with - ANSWER-tourmaline and beryl in
pegmatites
how heavy an object is in relation to its size - ANSWER-density
A two-phase inclusion is a cavity in a gem that's typically filled with a -
ANSWER-liquid and a gas
which type of twinning is caused by environmental change after a gem forms -
ANSWER-polysynthetic
which element caused red in ruby and green in emerald - ANSWER-chromium
A unit cell defines a mineral's - ANSWER-basic identity
which type of twinning looks as if two crystal halves are mirror images -
ANSWER-contact twinning
crystals that grow in a flux that is highly saturated with the necessary elements
tend to be - - ANSWER-small
which is classified in the orthorhombic crystal system - ANSWER-topaz
Which gems are cryptocrystalline aggregates? - ANSWER-Chalcedony and
turquoise
Atoms in a gem that aren't part of its essential chemical composition are called -
ANSWER-trace elements
CORRECT ANSWERS LATEST 2025
By what date had Kokichi Mikimoto begun culturing whole pearls - ANSWER-
1908
Synthetic gem materials - ANSWER-Are not minerals
which of the following is an organic gem - ANSWER-amber
which of the following is amorphous - ANSWER-amber
a natural material that's made up of a mass of one or more kinds of mineral crystals
is - ANSWER-rock
what group does alamandine belong to - ANSWER-garnet
A gem produced by, or derived from, a living organism is - ANSWER-organic
which of the following is a gem variety - ANSWER-demantoid
the world's largest gem-consuming market is - ANSWER-the US
a substance that consists of atoms of only one kind is a - ANSWER-chemical
element
,Media attention in the 1990s regarding its treatment reduced consumer confidence
in - ANSWER-emerald
a natural, inorganic substance with a characteristic chemical composition and usual
crystal structure is a - ANSWER-mineral
most gems are - ANSWER-minerals
To be a gem, a mineral must be beautiful, durable, and - ANSWER-rare
a broad gem category based on chemical composition and crystal structure is called
a - ANSWER-gem species
Many colored stones are mined by - ANSWER-independent miners using small-
scale mining methods.
Rocks altered by heat and pressure beneath Earth's surface are - ANSWER-
metamorphic
Which type of deposit is usually the most profitable for colored stone mining? -
ANSWER-secondary
Which gem can crystallize in volcanic rock from gasses released by magma? -
ANSWER-red beryl
Emeralds are rarely found in placer deposits because they're - ANSWER-unable to
withstand much abrasion
,Which is a workable alluvial deposit of gem minerals with economic potential? -
ANSWER-placers
Which is a deposit where gems eroded from the source rock and remained in place
nearby? - ANSWER-eluvial
from granite, pegmatite gems get exotic elements like - ANSWER-beryllium,
boron, and lithium
Myanmar's famous Mogok ruby deposits were formed by - ANSWER-
metamorphic process
most of the gems in tanzania's umba river valley are formed in - ANSWER-placer
deposits
A deposit where gems are found in the rock that where they formed is called -
ANSWER-primary deposit
Which is a key locality for hydrothermal gems? - ANSWER-Ouro Preto, Brazil
Heat and pressure transform limestone into - ANSWER-marble
which gem form by metamophosis - ANSWER-tanzanite
Most gemstones form in the - ANSWER-continental crust
, kunzite is most often associated with - ANSWER-tourmaline and beryl in
pegmatites
how heavy an object is in relation to its size - ANSWER-density
A two-phase inclusion is a cavity in a gem that's typically filled with a -
ANSWER-liquid and a gas
which type of twinning is caused by environmental change after a gem forms -
ANSWER-polysynthetic
which element caused red in ruby and green in emerald - ANSWER-chromium
A unit cell defines a mineral's - ANSWER-basic identity
which type of twinning looks as if two crystal halves are mirror images -
ANSWER-contact twinning
crystals that grow in a flux that is highly saturated with the necessary elements
tend to be - - ANSWER-small
which is classified in the orthorhombic crystal system - ANSWER-topaz
Which gems are cryptocrystalline aggregates? - ANSWER-Chalcedony and
turquoise
Atoms in a gem that aren't part of its essential chemical composition are called -
ANSWER-trace elements
