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Abrasion: Tiny nicks
along facet junctions, producing white fuzzy lines instead of
sharp crisp facet edges.
Baguette: A step cut in the shape of a small
rectangular stone. May be tapered at one end.
Bearded girdle, or Bearding: Tiny, numerous, hairlike
fractures extending into the stone.
Bezel: A facet on the Crown, or upper part of the
Diamond above the Girdle.
Blemish: Surface imperfection external to the Diamond.
Bort: Industrial grade diamonds
Bow-Tie Effect: An effect caused by a shadowy area
visible in some fancy shapes, caused by light leaking out the
bottom of the Diamond.
Bruise: An inclusions consisting of surface crumbling,
often accompanied by tiny, rootlike feathers .
Burned Facet: This facet may appear whitish, or burnt,
as a result of the cutter polishing the facet "against the
grain".
Carat Weight: The metric carat, which equals 0.200
gram, is the standard unit of weight for diamonds and most
other gems. If other factors are equal, the more a stone
weighs, the more valuable it will be.
Cavity: An inclusion consisting of a large or deep
opening in the stone.
Chip: A tiny piece missing, caused by normal wear and
tear, or by cutting.
Clarity: A stone's relative position on a flawless to
imperfect scale. Clarity characteristics are classified as
inclusions (internal) or blemishes (external). The size,
number, position, nature, and color or relief of
characteristics determine the clarity grade. Very few diamonds
are flawless, that is, show no inclusions or blemishes when
examined by a skilled grader under 10X magnification. If other
factors are equal, flawless stones are most valuable.
Cloud: A group of tiny white inclusions which result in
a milky or cloudy appearance.
Coated Diamond: A diamond colored by a surface coating
which masks the true body-color; the coating may be extensive
(entire pavilion, for example), but is more often limited to
one or two pavilion facets or a spot on the girdle.
Color: Grading color in the normal range involves
deciding how closely a stone's bodycolor approaches
colorlessness. Most diamonds have at least a trace of yellow
or brown bodycolor. With the exception of some natural fancy
colors, such as blue, pink, purple, or red, the colorless
grade is the most valuable.
Crown: The upper part of the diamond above the girdle.
Consists of a large flat area on top called a table, and
several facets below it.
Culet: The smallest facet at the bottom of the diamond.
Cut: The proportions and finish of a polished diamond
(also called make). Cut can also mean shape, as in emerald cut
or marquise cut. Proportions are the size and angle
relationships between the facets and different parts of the
stone. Finish includes polish and details of facet shape and
placement. Cut affects both the weight yield from rough and
the optical efficiency of the polished stone; the more
successful the cutter is in balancing these considerations,
the more valuable the stone will be.
Emerald cut: A step cut, usually rectangular.
Extra Facet: A facet placed without regard for symmetry
and not required by the cutting style.
Facet: Plane, polished surface of a diamond.
Faceted Girdle: Sometimes cutters polish the girdle
into 32 facets.
Fancy Diamond: A diamond with an attractive natural
bodycolor other than light yellow or light brown.
Feather: A separation or break due to either cleavage
or fracture, often white and feathery in appearance.
Flaw: An imperfection of a stone.
Fracture: A crack on the Diamond's surface.
Girdle: The outer edge or the widest part of the
diamond forming a band around the stone.
Grain Center: A small area of concentrated crystal
structure distortion, usually associated with pinpoints.
Hardness: Mineral's resistance to scratching on
a smooth surface. Mohs scale of relative hardness consists of
10 minerals, each scratching all those below it in scale and
being scratched by all those above it.
Hue: Pure, spectral (prismatic) color. Hues
include gradations and mixtures of red, organe, yellow, green,
blue, violet and purple.
Included Crystal: A mineral crystal contained in a
diamond.
Inclusion: Imperfection internal to the Diamond.
Internal Graining: Internal indications of irregular
crystal growth. May appear milky, like faint lines or streaks,
or may be colored or reflective.
Irradiated diamond: A diamond which has been exposed to
radiation.
Knot: An included diamond crystal which reaches the
surface of a polished diamond.
Laser Drill Hole: A tiny tube made by a laser. The
surface opening may resemble a pit, while the tube usually
looks needle-like.
Loupe: Magnifying glass usually of 10X.
Melee: Small Diamonds under .20 carat.
Mohs scale: The ten-point scale of mineral hardness,
keyed arbitrarily to the minerals talc, gypsum, calcite,
fluorite, apatite, orthoclase, quartz, topaz, corundum, and
diamond.
Natural: Part of the rough Diamond remaining on the
Diamond, having survived the cutting process. This is usually
the sign of a good cutter attempting to maximize the weight
retention of the rough Diamond.
Needle: A long, thin included crystal which looks like
a tiny rod.
Nick: A notch near the girdle or a facet edge.
Off-Make: A poorly proportioned Diamond.
Old European Cut: Early round cut similar to the Round
Brilliant Cut, but carrying a very small table and heavy
crown. Not as popular today because it does not return the
same brilliance as the modern brilliant.
Pavilion: The bottom part of the Diamond, below the
girdle.
Pinpoints: Miniscule spots internal to a Diamond. A
cluster of pinpoints can form a cloud.
Pit: A tiny opening, often looking like a white dot.
Point: 100th of a carat.
Polish Lines: Tiny parallel lines left by polishing.
Fine parallel ridges confined to a single facet, caused by
crystal structure irregularities, or tiny parallel polished
grooves produced by irregularities in the scaife surface.
Polish Mark: Surface clouding caused by excessive heat
(also called burn mark, or burned facet), or uneven polished
surface resulting from structural irregularities.
Rough Girdle: A grainy or pitted girdle surface, often
with nicks.
Round Brilliant cut: The most common cut containing 58
facets. Also the most brilliant cut, in terms of most
efficient use of light to increase brilliance and fire, hence
the name.
Saturation: A color's position on a neutral to vivid
scale.
Scratch: A linear indentation normally seen as a fine
white line, curved or straight.
Spread stone: A Diamond with a large table and a thin
crown height.
Surface Graining: Surface indication of structural
irregularity. May resemble faint facet junction lines, or
cause a grooved or wavy surface, often cross facet junctions.
Tone: A color's position on a colorless-to-black scale.
Treated Diamond: A diamond with a bodycolor induced by
some form of artificial irradiation, often in conjunction with
controlled heating (known as annealing).
Twinning Wisp: A cloudy area produced by crystal
structure distortion, usually associated with twinning planes.
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