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Glossary of Diamond Essentials

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The angle formed by the bezel facets and the girdle plane
Crown Angle

The separation of the white ligth into spectral colors
Dispersion
cutting style thats developed, named and promoted by a specific manufactuer
Branded cut
The birghtness created by the combination of all the whith light feflections from the surfact and the inside of a polished diamond
Brilliance
cutting style with trainglar or kite shaped facets that radiate from the center toward the girdle
Brilliant cut
the collective term for inclusions and blemishes
Clarity Chacteristics
top part of the gem above the girdle
Crown
Small facet at the bottom of a finished gem
Culet
a gemstones ability to wothstand wear, heat and chemicals
Durability
a flat, polished surface on a finished gem
Facet
any gemstone shape other than round
Fancy Cut

the flashes of color you see in a polished gem
Fire
four VALUE factors (color, clarity, cut and carat) that descripe the quality of a finished diamond
Four C's
rough gem material that requires normal processing to produce a polished gem suitalbe for use in jewelry
Gem Quality
The narrow section of a finished gem that forms the boundary between the crown and the pavilion and functions as the gems setting edge.
Girdle
How well a gemstone resists SCRATCHES and ABRASION
Hardness
Clarity characteristic totally enclosed in a polished gemstone or extending into it from the surface
Inclusion
rough gem material suitable for the use in tools, drills, abrasives and other indusrial applications.
Industrial quality
A unit of measure for hte fineness of gold
Karat
the international unit of measurement for gem weight. One carat equals 1/5th of a gram (.200g)
Metric carat
cut that combines brilliant-cut and step cut styles
Mixed cut
ranking of the relative hardness of 10 minerals
Mohs scale
rough gem materialthat requires substantially more processing thatn gem-quality rough t produce a polished gem suitable for use in jewelry
Near-Gem quality
lower part of a faceted gem below the girdle
Pavilion
One hundredth of a carat (.01ct)
Point
The flashes of light you see when the diamond, the light or the observer moves
Scintillation
A natural or manmade material that RESEMBLES a gem. Also called an imitation.
SImulant
A round stone with 17 or 18 facets
Single cut
a round brilliant cut stone with 57 or 58 facets. Often called a full cut.
Standard round brilliant
a cutting syle that features long, narrow facets in rows (usually 3) parallel to the girdle on both the crown and pavilion.
Step Cut
a manmade gem with essentially the same chemical composition, crystal structure and properites asas a natural gem.
Synthetic gem
Damage caused by sudden extreme temperature changes
Thermal shock
How well a gemstone resists breaking and chipping
Toughness
features uses to judge the quality and value of all gemstones
Value factors
Microscopse are useful tools in a retail setting True or False?
True
By hiding clarity characeristics, a cutter can improve the clarity of a diamond, True or False?
True
Fracture filling imporves the apparent or actual clarity of a diamond?
Apparent
Blemishes usually effect the top two clarity grades.. while inclusions effect ALL graded, True or False?

True
A key colored diagram of a gemstones significant clarity charactersitics
Plot
Part of the rough crystals origional surface left on a fashioned diamond
A Natural
Forming the basic face up outline of a diamond to prepare it for faceting
Bruting
A collective term for diamond CLEAVEGES and FRACTURES
Feather
Treatment that involves injecting molten glass substance into a diamonds surface-reaching feathers or laser drill holes
Fracture Filling
Descripes a diamond that might have surface blemished, but shows no inclusions at 10x
Loupe Clean
A general term for included stones
Pique
A flawless diamond may have what characteristic?
Extra facets on the Pavilion not visable face up
5 factors which determine the overall effect of a clarity characteristic are:
Size; Number; Position; Nature and Relief
Characteristics are enslosed within a gemstone. They may begin at the surface and move inward
Inclusion
Diamonds which contain minute inclusions that are difficult for an experienced grader to see under 10x
Clarity range VVS
When a diamond shows no inclusions under 10x by an experienced grader
Clarity range IF
When a diamond shows no inclusions or blemishes under 10x by an experienced grader
Clarity range F
(BG) Tiny feathers extending in from the girdle, created during the bruting process
Bearded Girdle
(Br) tiny opening or hole accompanied by tine, root-like feathers
Bruise
(Cv) an opening or hole created when a crystal is pullled out, or when a feather breaks away
Inclusion "Cavity"
(Cld) a hazy or milky area make up of a number of very small inclusions grouped together
Inclustion "Cloud"
(Ftr) a separation or break that reaches the surface, and is often white and feathery or shiny in appearance.
Feather
(GrCnt) a small area of concentrated crystal structure distortion, usually with a pinpoint-like or thread like appearance
Grain Center
(Xtl)a mineral crystal enclosed within a diamond
Included crystal
internal indications of irregular crystal growth; may appear like faint lines or streaks agains a transparent background, or may appear milky, colored or reflective.
Internal graining
laser drilling within a diamond that doesent reach the surfact; not plotted
Internal laser Drilling
a tiny tube made by a laser; the surface opening might resemble a pit, while the tube might resemble a needle
Laser drill hole
a long, thin included crystal that looks like a tiny rod
Needle
a very small included crystal, normally seen under 10x as a diny dot, either singly or in groups or strings
Pinpoint
a series of tiny nicks along facet junctions, producting white fuzzy lines instead of sharp facet edges
Abrasion
a facet placed without regard for symmerty and not required by the cutting style.
Extra Facet
wavy or bumpy area on teh surface ofa polished diamond
Lizard Skin
part of the orgional surface of rough diamonds surface that remains on the polished stone
Natural
fine parallel groves an ridges left on a gems facet as a result of the polishing process
Polish Lines
whitish film on the surface of a facet caused by excessive heat during polishing.
Polish Mark
a grainy or pitted girdle surface, often with nicks
Rough girdle
a linear indentation normally seen as a fine white line, curved or straight, with no apparent depth.
Scratch
Surface indication of structural irregularity; might appear as a groved or wavy surface; might cross facet junctions
Surface Graining
A gemstone heating process that can be used alonr or to stabilize irradiated color
Annealing
The basic color of a fancy colored gemstone
Color Characteristic
The combination ot TONE and SATURATION that determines how noticeable the color is.
Depth of Color
Naturally colored yellow and brown diamonds that exhibit color beyone the Z range, or that exhibit any othe color face up.
Fancy colored diamonds
The emission of visible light by a material when its exposed to ultraviolet radiation
Fluoresence
Your first impression of a color; the basic color of an object
Hue
A treatment that changes the clolor of a gem by exposing it to radioactive materials
Irradiaion
A set of color comparision diamonds that defines GIA's diamond color grades in the normal (D-Z) range
Masterstones
A general term for diamonds in teh G-to-J color range
Near-Colorless
Tanned of diamonds colrs from colorless to light yellow and light brown
Normal Color Range
A colors strength or intensity, ranging from a dull hue to a pure, vivid hue
Saturation
A colors degree of darkness or lightness
Tone
light wavelength that's invisiable to the human eye
Ultraviolet
Each letter grade in the GIA color scal represents?
A range in color
The top grade of the NORMAL GIA color range is?
D
The most common color of fluorescencs in gem quality diamond is?
Blue
Which of the following grades has the most yellow? D, G, I, H
I
The most commonly encountered colors amoung fancy colored diamonds are?
Brown and Yellow
Which masterstone does GIA Gem Trade Lab use to determine if a natural yellow diamonds qualifies as a fancy yellow?
Color grade Z
The color grade a light yellow or brown diamond, graders compare it to a masterstone for?
Hue, Tone and Saturation
The annealing of irradiated diamonds to stabilize their color is done by?
Heating
The combination of tone and saturation that determines how noticable a color is, is know as?
Hue
When mounted, G,H and I diamonds can look?
Colorless face up
If all factors are equal, the more rare diamonds are?
RED And PURPLE
Irradiated diamonds might change color when expesed to?
Heat
Most consumers can easliy see color beyond the color grade?
M

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