GIA DIAMONDS AND DIAMOND GRADING
GLOSSARY TERMS Questions and Answers
Latest Versions 2025 TOP RATED A+
Possessing different physical or optical properties in different crystal
directions. Right Ans - Doubly refractive (anisotropic)
The retail portion of the diamond value chain. Right Ans - Downstream
A horizontal tunnel drilled through a diamond pipe. Right Ans - Drift
A prospector's term for diamond deposits away from water. Right Ans -
Dry diggings
A measure of how well an electrical current passes through a material.
Right Ans - Electrical conductivity
The range of wavelengths of radiant energy extending from high energy to low
energy, including visible light. Right Ans - Electromagnetic spectrum
A set of policies and processes that enable an organization to reduce
environmental impacts and increase operating efficiency. Right Ans -
Environmental management system
A geological process that delivers material (sometimes diamonds) to the
surface. Right Ans - Eruption
The amount of time light has to enter a camera. Right Ans - Exposure
Visible to the unaided eye, without magnification. Right Ans - Eye-visible
Any gemstone shape other than a standard round brilliant. Right Ans -
Fancy cut
General trade term for a break in a diamond. Right Ans - Feather
,The quality of the polish and precision of the cut of a fashioned gemstone.
Right Ans - Finish
A flash of changing color seen in a fracture-filled diamond when you look
parallel to the filled inclusion and rock the diamond back and forth under
magnification. Right Ans - Flash effect
Emission of visible light by a material when it's exposed to ultraviolet
radiation. Right Ans - Fluorescence
Gemstone or simulant with a thin metallic foil or mirroring film applied to its
pavilion. Right Ans - Foilback
Treatment that involves injecting a molten glass substance into a diamond's
surface-reaching feathers or laser drill-holes. Right Ans - Fracture filling
A faceting style that replaces the large bezel facets at the points of marquises,
pears, and hearts with star and upper half facets. Right Ans - French tips
Diamonds that meet certain criteria to be used as gems in the jewerly market.
Right Ans - Gem quality diamonds
An analysis that determines the chemical composition of a sample. Right
Ans - Geochemical testing
The rate of temperature increase with depth in the earth. Right Ans -
Geothermal gradient
The width of a fashioned gem's girdle. Right Ans - Girdle thickness
Girdle thickness expressed as a percentage of average girdle diameter.
Right Ans - Girdle thickness percentage
A well-shaped, transparent, octahedral diamond crystal with sharp, square
edges. Right Ans - Glassie
Crystal distortion caused during growth when one part of the lattice is offset
in relation to the rest. Right Ans - Glide plane
, Inclusions or blemishes that establish the clarity grade of a diamond. Right
Ans - Grade-setting characteristics
Visible, shadow-like lines in a diamond caused by irregularities in the crystal
structure. Right Ans - Graining (grain lines)
Graphite formation around a diamond's mineral inclusions and feathers that
results from the extreme conditions of HPHT processing. Right Ans -
Graphitization
An apparatus that uses diamonds' affinity for grease to separate them from
other minerals. Right Ans - Grease belt
Visible features on the surface of a minderal crystal that reflect its internal
growth and development. Right Ans - Growth marks
A three-dimensional region with a common crystallographic growth plate.
Right Ans - Growth sector
Characteristic crystal shape of a specific mineral. The characteristic external
crystal shape or form of a mineral. Right Ans - Habit
How heavy an object feels in relation to its size. Right Ans - Heft
Your first impression of a color; the basic color of an object. The first
impression of an object's basic color. Right Ans - Hue
Rock formed by the crystallization of molten material. A category of rocks
formed from a molten state. Right Ans - Igneous Rock
Diamonds that can be repolished to improve their clarity to a VVS1 or VVS2
grade. Right Ans - Improvable
Clarity characteristic totally enclosed in a polished gemstone or extending into
it from the surface. Right Ans - Inclusion
Minerals formed together with diamonds at great depths and brought to the
surface by the same kimberlites or lamproites. Right Ans - Indicator
minerals
GLOSSARY TERMS Questions and Answers
Latest Versions 2025 TOP RATED A+
Possessing different physical or optical properties in different crystal
directions. Right Ans - Doubly refractive (anisotropic)
The retail portion of the diamond value chain. Right Ans - Downstream
A horizontal tunnel drilled through a diamond pipe. Right Ans - Drift
A prospector's term for diamond deposits away from water. Right Ans -
Dry diggings
A measure of how well an electrical current passes through a material.
Right Ans - Electrical conductivity
The range of wavelengths of radiant energy extending from high energy to low
energy, including visible light. Right Ans - Electromagnetic spectrum
A set of policies and processes that enable an organization to reduce
environmental impacts and increase operating efficiency. Right Ans -
Environmental management system
A geological process that delivers material (sometimes diamonds) to the
surface. Right Ans - Eruption
The amount of time light has to enter a camera. Right Ans - Exposure
Visible to the unaided eye, without magnification. Right Ans - Eye-visible
Any gemstone shape other than a standard round brilliant. Right Ans -
Fancy cut
General trade term for a break in a diamond. Right Ans - Feather
,The quality of the polish and precision of the cut of a fashioned gemstone.
Right Ans - Finish
A flash of changing color seen in a fracture-filled diamond when you look
parallel to the filled inclusion and rock the diamond back and forth under
magnification. Right Ans - Flash effect
Emission of visible light by a material when it's exposed to ultraviolet
radiation. Right Ans - Fluorescence
Gemstone or simulant with a thin metallic foil or mirroring film applied to its
pavilion. Right Ans - Foilback
Treatment that involves injecting a molten glass substance into a diamond's
surface-reaching feathers or laser drill-holes. Right Ans - Fracture filling
A faceting style that replaces the large bezel facets at the points of marquises,
pears, and hearts with star and upper half facets. Right Ans - French tips
Diamonds that meet certain criteria to be used as gems in the jewerly market.
Right Ans - Gem quality diamonds
An analysis that determines the chemical composition of a sample. Right
Ans - Geochemical testing
The rate of temperature increase with depth in the earth. Right Ans -
Geothermal gradient
The width of a fashioned gem's girdle. Right Ans - Girdle thickness
Girdle thickness expressed as a percentage of average girdle diameter.
Right Ans - Girdle thickness percentage
A well-shaped, transparent, octahedral diamond crystal with sharp, square
edges. Right Ans - Glassie
Crystal distortion caused during growth when one part of the lattice is offset
in relation to the rest. Right Ans - Glide plane
, Inclusions or blemishes that establish the clarity grade of a diamond. Right
Ans - Grade-setting characteristics
Visible, shadow-like lines in a diamond caused by irregularities in the crystal
structure. Right Ans - Graining (grain lines)
Graphite formation around a diamond's mineral inclusions and feathers that
results from the extreme conditions of HPHT processing. Right Ans -
Graphitization
An apparatus that uses diamonds' affinity for grease to separate them from
other minerals. Right Ans - Grease belt
Visible features on the surface of a minderal crystal that reflect its internal
growth and development. Right Ans - Growth marks
A three-dimensional region with a common crystallographic growth plate.
Right Ans - Growth sector
Characteristic crystal shape of a specific mineral. The characteristic external
crystal shape or form of a mineral. Right Ans - Habit
How heavy an object feels in relation to its size. Right Ans - Heft
Your first impression of a color; the basic color of an object. The first
impression of an object's basic color. Right Ans - Hue
Rock formed by the crystallization of molten material. A category of rocks
formed from a molten state. Right Ans - Igneous Rock
Diamonds that can be repolished to improve their clarity to a VVS1 or VVS2
grade. Right Ans - Improvable
Clarity characteristic totally enclosed in a polished gemstone or extending into
it from the surface. Right Ans - Inclusion
Minerals formed together with diamonds at great depths and brought to the
surface by the same kimberlites or lamproites. Right Ans - Indicator
minerals
