GIA Colored Stones Complete Final Exam
questions and answers
Mineral - ANSWER>>A natural, inorganic substance with a characteristic chemical
composition and usually characteristic structure.
Mixed cut - ANSWER>>A cutting style that combines brilliant-cut and step cut
facets.
Abrasions - ANSWER>>Tiny nicks and pits caused by wear and damage to a gem's
facet edges or culet.
Absorption spectrum - ANSWER>>A pattern of dark vertical lines or bands shown
by certain gems when viewed through a spectroscope.
Adularescence - ANSWER>>The cloudy bluish white light in a moonstone, caused
by scattering of light.
Agate - ANSWER>>Chalcedony with a curved or angular bands or layers that differ
in color and transparency .
Aggregate - ANSWER>>A mass of tiny, randomly oriented crystals.
Akoya - ANSWER>>Common name for the Pinctada fucata oyster and the natural
or cultured pearls it produces.
Allochromatic - ANSWER>>A gem colored by trace elements in its crystal
structure.
Alluvial deposit - ANSWER>>A deposit where gems are eroded from their source
rock, then transported away from their source and further concentrated.
,Amorphous - ANSWER>>Lacking a regular crystal structure.
Aragonite - ANSWER>>A crystalized form of calcium carbonate found in nacre.
Assembled stone - ANSWER>>Two or more separate pieces of material joined to
form a unit.
Asterism - ANSWER>>Crossing of chatoyant bands, creating a star in the dome of
cabochon.
Atom - ANSWER>>The basic structural unit of all matter.
Aventurescence - ANSWER>>A glittery effect caused by light reflecting from small,
flat inclusions within a gemstone.
Background color - ANSWER>>An opal's bodycolor, independent of its play-of-
color.
Bead nucleus - ANSWER>>A bead used as the core of a cultured pearl, usually
made from a freshwater mussel shell.
Bleaching - ANSWER>>A treatment that uses chemicals to lighten or remove
color.
Blemish - ANSWER>>Characteristic or irregularity confined to the surface of a
polished gemstone.
Blue Sheen - ANSWER>>Trade term for a highly prized, vivid blue adularescence
displayed by the finest moonstone.
Bodycolor - ANSWER>>A gemstone's basic color, determined by its selective
absorption of light.
,Botryoidal - ANSWER>>A crystal growth habit with a bumpy appearance similar to
a bunch of grapes.
Boulder opal - ANSWER>>Thin layers of precious opal, cut to include matrix.
Boule - ANSWER>>A cylindrical synthetic crystal produced by the flame-fusion
process.
Brilliance - ANSWER>>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 - ANSWER>>Cutting style with triangular or kite-shaped facets that
radiate from the center toward girdle.
Cabochon - ANSWER>>A smoothly rounded polished gem with a domed top and a
flat or curved base.
Calcareous concretion - ANSWER>>A non-nacreous natural "pearl".
Calibrated sizes - ANSWER>>Gemstone sizes cut to fit standard mountings.
Cameo - ANSWER>>A gem carving style in which the design often a women's
profile, projects slightly from a flat or curved surface.
Cavity - ANSWER>>An opening that extends into a gem from the surface.
Centipedes - ANSWER>>Tiny tension cracks in a moonstone that interfere with
adularescence and reduce value.
Ceramic process - ANSWER>>A process in which ground powder is heated,
sometimes under pressure, to produce a fine-grained solid material.
, Certificate of origin - ANSWER>>A document that indicates a stone's geographic
origin, based on its inclusions and trace element chemistry.
Chalcedony - ANSWER>>A cryptocrystalline quartz aggregate.
Charge transfer - ANSWER>>A process where the electrons that selectively absorb
light are passed back and forth between neighboring impurity ions.
Chatoyancy - ANSWER>>Bands of light in certain gems, caused by reflection of
light from many parallel, needle-like inclusions or hollow tubes.
Chemical composition - ANSWER>>Kinds and relative quantities of atoms that
make up a material.
Chemical element - ANSWER>>A substance that consists of atoms of only one
kind.
Chip - ANSWER>>A damaged area on a gem, usually near the girdle.
Chrome tourmaline - ANSWER>>Trade term for a vibrant green tourmaline that's
colored by traces of vanadium, chromium, or both.
Circled pearl - ANSWER>>A pearl with one or more grooved or ridged rings all the
way around it.
Cleavage - ANSWER>>A smooth, flat break in a gemstone parallel to planes of
atomic weakness, caused by weak or fewer bonds between atoms or both.
Cloud - ANSWER>>Any hazy or milky area that cannot be described as a feather,
fingerprint, or group of included crystals or needles.
questions and answers
Mineral - ANSWER>>A natural, inorganic substance with a characteristic chemical
composition and usually characteristic structure.
Mixed cut - ANSWER>>A cutting style that combines brilliant-cut and step cut
facets.
Abrasions - ANSWER>>Tiny nicks and pits caused by wear and damage to a gem's
facet edges or culet.
Absorption spectrum - ANSWER>>A pattern of dark vertical lines or bands shown
by certain gems when viewed through a spectroscope.
Adularescence - ANSWER>>The cloudy bluish white light in a moonstone, caused
by scattering of light.
Agate - ANSWER>>Chalcedony with a curved or angular bands or layers that differ
in color and transparency .
Aggregate - ANSWER>>A mass of tiny, randomly oriented crystals.
Akoya - ANSWER>>Common name for the Pinctada fucata oyster and the natural
or cultured pearls it produces.
Allochromatic - ANSWER>>A gem colored by trace elements in its crystal
structure.
Alluvial deposit - ANSWER>>A deposit where gems are eroded from their source
rock, then transported away from their source and further concentrated.
,Amorphous - ANSWER>>Lacking a regular crystal structure.
Aragonite - ANSWER>>A crystalized form of calcium carbonate found in nacre.
Assembled stone - ANSWER>>Two or more separate pieces of material joined to
form a unit.
Asterism - ANSWER>>Crossing of chatoyant bands, creating a star in the dome of
cabochon.
Atom - ANSWER>>The basic structural unit of all matter.
Aventurescence - ANSWER>>A glittery effect caused by light reflecting from small,
flat inclusions within a gemstone.
Background color - ANSWER>>An opal's bodycolor, independent of its play-of-
color.
Bead nucleus - ANSWER>>A bead used as the core of a cultured pearl, usually
made from a freshwater mussel shell.
Bleaching - ANSWER>>A treatment that uses chemicals to lighten or remove
color.
Blemish - ANSWER>>Characteristic or irregularity confined to the surface of a
polished gemstone.
Blue Sheen - ANSWER>>Trade term for a highly prized, vivid blue adularescence
displayed by the finest moonstone.
Bodycolor - ANSWER>>A gemstone's basic color, determined by its selective
absorption of light.
,Botryoidal - ANSWER>>A crystal growth habit with a bumpy appearance similar to
a bunch of grapes.
Boulder opal - ANSWER>>Thin layers of precious opal, cut to include matrix.
Boule - ANSWER>>A cylindrical synthetic crystal produced by the flame-fusion
process.
Brilliance - ANSWER>>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 - ANSWER>>Cutting style with triangular or kite-shaped facets that
radiate from the center toward girdle.
Cabochon - ANSWER>>A smoothly rounded polished gem with a domed top and a
flat or curved base.
Calcareous concretion - ANSWER>>A non-nacreous natural "pearl".
Calibrated sizes - ANSWER>>Gemstone sizes cut to fit standard mountings.
Cameo - ANSWER>>A gem carving style in which the design often a women's
profile, projects slightly from a flat or curved surface.
Cavity - ANSWER>>An opening that extends into a gem from the surface.
Centipedes - ANSWER>>Tiny tension cracks in a moonstone that interfere with
adularescence and reduce value.
Ceramic process - ANSWER>>A process in which ground powder is heated,
sometimes under pressure, to produce a fine-grained solid material.
, Certificate of origin - ANSWER>>A document that indicates a stone's geographic
origin, based on its inclusions and trace element chemistry.
Chalcedony - ANSWER>>A cryptocrystalline quartz aggregate.
Charge transfer - ANSWER>>A process where the electrons that selectively absorb
light are passed back and forth between neighboring impurity ions.
Chatoyancy - ANSWER>>Bands of light in certain gems, caused by reflection of
light from many parallel, needle-like inclusions or hollow tubes.
Chemical composition - ANSWER>>Kinds and relative quantities of atoms that
make up a material.
Chemical element - ANSWER>>A substance that consists of atoms of only one
kind.
Chip - ANSWER>>A damaged area on a gem, usually near the girdle.
Chrome tourmaline - ANSWER>>Trade term for a vibrant green tourmaline that's
colored by traces of vanadium, chromium, or both.
Circled pearl - ANSWER>>A pearl with one or more grooved or ridged rings all the
way around it.
Cleavage - ANSWER>>A smooth, flat break in a gemstone parallel to planes of
atomic weakness, caused by weak or fewer bonds between atoms or both.
Cloud - ANSWER>>Any hazy or milky area that cannot be described as a feather,
fingerprint, or group of included crystals or needles.
