GIA COLORED STONES EXAM QUESTIONS AND ANSWERS
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Mineral - Answers A natural, inorganic substance with a characteristic chemical composition
and usually characteristic structure.
Mixed cut - Answers A cutting style that combines brilliant-cut and step cut facets.
Abrasions - Answers Tiny nicks and pits caused by wear and damage to a gem's facet edges or
culet.
Absorption spectrum - Answers A pattern of dark vertical lines or bands shown by certain
gems when viewed through a spectroscope.
Adularescence - Answers The cloudy bluish white light in a moonstone, caused by scattering
of light.
Agate - Answers Chalcedony with a curved or angular bands or layers that differ in color and
transparency .
Aggregate - Answers A mass of tiny, randomly oriented crystals.
Akoya - Answers Common name for the Pinctada fucata oyster and the natural or cultured
pearls it produces.
Allochromatic - Answers A gem colored by trace elements in its crystal structure.
, Alluvial deposit - Answers A deposit where gems are eroded from their source rock, then
transported away from their source and further concentrated.
Amorphous - Answers Lacking a regular crystal structure.
Aragonite - Answers A crystalized form of calcium carbonate found in nacre.
Assembled stone - Answers Two or more separate pieces of material joined to form a unit.
Asterism - Answers Crossing of chatoyant bands, creating a star in the dome of cabochon.
Atom - Answers The basic structural unit of all matter.
Aventurescence - Answers A glittery effect caused by light reflecting from small, flat
inclusions within a gemstone.
Background color - Answers An opal's bodycolor, independent of its play-of-color.
Bead nucleus - Answers A bead used as the core of a cultured pearl, usually made from a
freshwater mussel shell.
Bleaching - Answers A treatment that uses chemicals to lighten or remove color.
Blemish - Answers Characteristic or irregularity confined to the surface of a polished
gemstone.
, Blue Sheen - Answers Trade term for a highly prized, vivid blue adularescence displayed by
the finest moonstone.
Bodycolor - Answers A gemstone's basic color, determined by its selective absorption of light.
Botryoidal - Answers A crystal growth habit with a bumpy appearance similar to a bunch of
grapes.
Boulder opal - Answers Thin layers of precious opal, cut to include matrix.
Boule - Answers A cylindrical synthetic crystal produced by the flame-fusion process.
Brilliance - Answers Light that eventually returns to the eye after entering a gem through the
crown, reflecting off its pavilion facets, and exiting back through the crown.
Brilliant cut - Answers Cutting style with triangular or kite-shaped facets that radiate from the
center toward girdle.
Cabochon - Answers A smoothly rounded polished gem with a domed top and a flat or
curved base.
Calcareous concretion - Answers A non-nacreous natural "pearl".
Calibrated sizes - Answers Gemstone sizes cut to fit standard mountings.
Cameo - Answers A gem carving style in which the design often a women's profile, projects
slightly from a flat or curved surface.
, Cavity - Answers An opening that extends into a gem from the surface.
Centipedes - Answers Tiny tension cracks in a moonstone that interfere with adularescence
and reduce value.
Ceramic process - Answers A process in which ground powder is heated, sometimes under
pressure, to produce a fine-grained solid material.
Certificate of origin - Answers A document that indicates a stone's geographic origin, based
on its inclusions and trace element chemistry.
Chalcedony - Answers A cryptocrystalline quartz aggregate.
Charge transfer - Answers A process where the electrons that selectively absorb light are
passed back and forth between neighboring impurity ions.
Chatoyancy - Answers Bands of light in certain gems, caused by reflection of light from many
parallel, needle-like inclusions or hollow tubes.
Chemical composition - Answers Kinds and relative quantities of atoms that make up a
material.
Chemical element - Answers A substance that consists of atoms of only one kind.
Chip - Answers A damaged area on a gem, usually near the girdle.
Chrome tourmaline - Answers Trade term for a vibrant green tourmaline that's colored by
traces of vanadium, chromium, or both.
RATED A+ 2025/2026 100% VERIFIED CORRECT NEW!!
Mineral - Answers A natural, inorganic substance with a characteristic chemical composition
and usually characteristic structure.
Mixed cut - Answers A cutting style that combines brilliant-cut and step cut facets.
Abrasions - Answers Tiny nicks and pits caused by wear and damage to a gem's facet edges or
culet.
Absorption spectrum - Answers A pattern of dark vertical lines or bands shown by certain
gems when viewed through a spectroscope.
Adularescence - Answers The cloudy bluish white light in a moonstone, caused by scattering
of light.
Agate - Answers Chalcedony with a curved or angular bands or layers that differ in color and
transparency .
Aggregate - Answers A mass of tiny, randomly oriented crystals.
Akoya - Answers Common name for the Pinctada fucata oyster and the natural or cultured
pearls it produces.
Allochromatic - Answers A gem colored by trace elements in its crystal structure.
, Alluvial deposit - Answers A deposit where gems are eroded from their source rock, then
transported away from their source and further concentrated.
Amorphous - Answers Lacking a regular crystal structure.
Aragonite - Answers A crystalized form of calcium carbonate found in nacre.
Assembled stone - Answers Two or more separate pieces of material joined to form a unit.
Asterism - Answers Crossing of chatoyant bands, creating a star in the dome of cabochon.
Atom - Answers The basic structural unit of all matter.
Aventurescence - Answers A glittery effect caused by light reflecting from small, flat
inclusions within a gemstone.
Background color - Answers An opal's bodycolor, independent of its play-of-color.
Bead nucleus - Answers A bead used as the core of a cultured pearl, usually made from a
freshwater mussel shell.
Bleaching - Answers A treatment that uses chemicals to lighten or remove color.
Blemish - Answers Characteristic or irregularity confined to the surface of a polished
gemstone.
, Blue Sheen - Answers Trade term for a highly prized, vivid blue adularescence displayed by
the finest moonstone.
Bodycolor - Answers A gemstone's basic color, determined by its selective absorption of light.
Botryoidal - Answers A crystal growth habit with a bumpy appearance similar to a bunch of
grapes.
Boulder opal - Answers Thin layers of precious opal, cut to include matrix.
Boule - Answers A cylindrical synthetic crystal produced by the flame-fusion process.
Brilliance - Answers Light that eventually returns to the eye after entering a gem through the
crown, reflecting off its pavilion facets, and exiting back through the crown.
Brilliant cut - Answers Cutting style with triangular or kite-shaped facets that radiate from the
center toward girdle.
Cabochon - Answers A smoothly rounded polished gem with a domed top and a flat or
curved base.
Calcareous concretion - Answers A non-nacreous natural "pearl".
Calibrated sizes - Answers Gemstone sizes cut to fit standard mountings.
Cameo - Answers A gem carving style in which the design often a women's profile, projects
slightly from a flat or curved surface.
, Cavity - Answers An opening that extends into a gem from the surface.
Centipedes - Answers Tiny tension cracks in a moonstone that interfere with adularescence
and reduce value.
Ceramic process - Answers A process in which ground powder is heated, sometimes under
pressure, to produce a fine-grained solid material.
Certificate of origin - Answers A document that indicates a stone's geographic origin, based
on its inclusions and trace element chemistry.
Chalcedony - Answers A cryptocrystalline quartz aggregate.
Charge transfer - Answers A process where the electrons that selectively absorb light are
passed back and forth between neighboring impurity ions.
Chatoyancy - Answers Bands of light in certain gems, caused by reflection of light from many
parallel, needle-like inclusions or hollow tubes.
Chemical composition - Answers Kinds and relative quantities of atoms that make up a
material.
Chemical element - Answers A substance that consists of atoms of only one kind.
Chip - Answers A damaged area on a gem, usually near the girdle.
Chrome tourmaline - Answers Trade term for a vibrant green tourmaline that's colored by
traces of vanadium, chromium, or both.
