GIA Colored
Stones(684 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.
Stones(684 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.
