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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: Tiny, numerous, hair like
fractures extending into the stone.
Bezel: A facet on the Crown, or upper part of the
Diamond above the Girdle.
Blemish: A clarity characteristic that occurs on
the surface of a diamond. Though some blemishes are
inherent to the original rough diamond, most are the
result of the environment the diamond has encountered
since it was unearthed.
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.
Brilliance: The brightness that seems to come
from the very heart of a diamond. It is the effect that
makes diamonds unique among all other gemstones. While
other gemstones also display brilliance, none have the
power to equal the extent of diamond's light-reflecting
power. Brilliance is created primarily when light enters
through the table, reaches the pavilion facets, and is
then reflected back out through the table, where the
light is most visible to your eye.
Brilliant Cut: One of three styles of faceting
arrangements. In this type of arrangement, all facets
appear to radiate out from the center of the diamond
toward its outer edges. It is called a brilliant cut
because it designed to maximize brilliance. Round
diamonds, ovals, radiant, princesses, hearts, marquises,
and pears all fall within this category of cut. Other
styles of faceting arrangements include the step cut (in
which facets are arranged in concentric rows around the
table and the culet) and the mixed cut (in which either
the crown or pavilion of a diamond is cut as a brilliant
cut, and the other part of the diamond is cut as a step
cut). Note: Some jewelers use the term "Brilliant cut"
as a synonym for "round diamond."
Bruise: An inclusions consisting of surface
crumbling, often accompanied by tiny, root like
feathers.
Burned Facet: This facet may appear whitish, or
burnt, as a result of the cutter polishing the facet
"against the grain".
Carat Weight:
Diamond
weight is calculated in carats. One full carat or 1.00
ct weighs 200 milligrams, which is one fifth of a gram.
A carat can also be divided into one hundred points. A
quarter of a carat diamond can be described as .25 ct ,
which can also be called a twenty-five pointer. A one
and a half carat diamond is also described as 1.50 ct.
Carbon Spots: An inaccurate term used by some
people in the jewelry industry to describe the
appearance of certain inclusions in a diamond. The term
refers to included crystals that have a dark appearance,
rather than a white or transparent appearance, when
viewed under a microscope. In most cases, these dark
inclusions are not visible to the naked eye, and do not
affect the brilliance of the diamond.
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: Clarity refers to the existence of
apparent interior and exterior characteristics in a
diamond. Some of these happen naturally and some happen
because of the pressure put upon the diamond during the
course of mining. inside characteristics are called
inclusions and outside characteristics are called
blemishes. Clarity characteristics guarantee that no two
diamonds are entirely similar. Many gemologists refer to
characteristic of clarity like a diamond's fingerprint.
Cleavage: The propensity of crystalline minerals,
such as diamond, to split in one or more directions
either along or parallel to certain planes, when struck
by a blow. Cleavage is one of the two methods used by
diamond cutters to split rough diamond crystals in
preparation for the cutting process (sawing is the other
method).
Cloud:
Clouds are actually a cluster of a number of exceedingly
minute inclusions that are too small to be noticeable
from one another, even when magnified under a
microscope, that’s why they are called clouds because
this cluster a lot of times looks like a soft
see-through cloud within the diamond.
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:
Diamond color grades range from D to Z however
only colors ranging between D through M are considered
to be in the standard color range. Diamonds whose color
is graded between D and F are naturally the most
valuable since they are much harder to find because of
their rarity. Diamonds graded between G and I, do not
have any visible color that can be seen by the untrained
eye.
Crown angle:
The crowns angles is the angle that exist sandwiched
between the girdle line and the bezel facets. Most
diamonds crown angles are between thirty and thirty five
degrees. Crown angles of 34.5 degrees are preferred by a
consensus of the diamond industries professional, though
other esteemed experts recommend a somewhat lower angle.
Crown:
The
crown is the upper part of a diamond the crown contains
32 facets besides for the table facet. The name of the
facets in the crown are - the 8 triangle like facets
bordering to the table are called star facets; the 8
kite shaped facets whose points touch both the table and
girdle are called bezel facets; and, the other sixteen
triangle like facets that help form the girdles border
are called the upper girdle facets. The crown facets are
most directly connected to a diamond's brilliance.
Culet:
Some round brilliant diamonds have a tiny, extra facet
on the bottom tip of the pavilion which is called the
culet. The culet's principle is to avoid damage to the
finest point of the pavilion while the diamond is being
handled before being set. When a diamond is looked at
face-up, a larger culet than "medium" may produce a
visual disturbance right in the middle of the table,
which is the most awful place to have any distraction.
Cut:
Cut refers to the angles and proportions skilled
craftsmen create in transforming rough diamonds. The cut
of a diamond meaning the roundness, the depth and width,
the uniformity of its facets — establish a diamond's
brilliancy. Many gemologists consider the factor of cut
to be the most important feature of diamonds because
even when a diamond has the perfect color and Clarity
grades, if it was poorly cut it will have dulled
brilliance.
Depth Percentage:
Total depth percentage is calculated by dividing the
diamonds total depth by the girdles diameter.
Depth: The height of the diamond starting from the culet
and up to
the table. The depth measurements are measured in millimeters.
Diamond Cutting: The method by which a rough
diamond that has been mined from the earth is shaped
into a finished, faceted stone. As a first step,
cleaving or sawing is often used to separate the rough
into smaller, more workable pieces that will each
eventually become an individual polished gem. Next,
bruiting grinds away the edges, providing the outline
shape (for example, heart, oval or round) for the gem.
Faceting is done in two steps: during blocking, the
table, culet, bezel and pavilion main facets are cut;
afterward, the star, upper girdle and lower girdle
facets are added. Once the fully faceted diamond has
been inspected and improved, it is boiled in
hydrochloric and sulfuric acids to remove dust and oil.
The diamond is then considered a finished, polished gem.
Diamond Gauge: An instrument that is used to
measure a diamond's length, width and depth in
millimeters.
Diamond: A crystal made up of 99.95% pure carbon
atoms arranged in an isometric, or cubic, crystal
arrangement. It is this unique arrangement of the carbon
atoms that makes diamond look and behave differently
from other pure carbon minerals such as graphite (the
soft black material used to make pencils).
Facet: The smooth, flat faces on the surface of a
diamond. They allow light to both enter a diamond and
reflect off its surface at different angles, creating
the wonderful play of color and light for which diamonds
are famous. The table below shows all the facets on a
round brilliant cut diamond. A round brilliant has 58
facets (or 57 if there is no culet).
Faceted Girdle: Sometimes cutters polish the
girdle into 32 facets.
Feathers:
These are small fractures in a diamond. Stress is what
usually causes them while the diamond was still growing.
This can occur on the inside of the diamond or on the
surface. The expression "feather" comes from the idea
that, when seen under a microscope, these fracture often
appear to have an imprecise, feathery shape to them.
Finish:
is an interpretive calculation of the quality of the
polish of a diamonds outside surface and also the
symmetry. Diamond shape affects this grade because each
shape is graded by its own cut characteristics and its
proportions and finish. Both factors the proportions and
the finish are measured in judgment of the overall cut
grade assigned to a diamond.
Flaw: An imperfection in a diamond.
Fluorescence:
Almost
thirty five percent of all gem quality diamonds glow or
fluoresce when they are exposed to what is called
"ultraviolet radiation(UV)". This happens when a
diamond's atomic structure meets with energy of the UV's
radiation. A lot of diamond owners may notice the
fluorescent in their diamond when they are exposed to
strong light or under the lights of a nightclub. The
color of fluorescence is usually blue, but some diamonds
can also show fluorescence in different colors such as
white, green, yellow, red or orange.
Fracture: A crack on the Diamond's exterior surface.
Gemological Institute of America (GIA): Founded
in 1931 by Roger Shipley, this non-profit organization
upholds the highest standards for grading diamonds and
other precious gems. The GIA has one of the
most-respected and well-regarded gemological
laboratories in the world; GIA was responsible for
developing and standardizing the diamond grading system
that is used today by nearly all other gem labs.
Girdle:
The
girdle is the widest point of a diamond dividing the
diamond's top and bottom parts. The girdle helps to the
underpinning of a set diamond and can be the most
helpful or a source of danger.
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, orange, yellow,
green, blue, violet and purple.
Included Crystal: A mineral crystal contained in
a diamond. Inclusion: Imperfection internal to the
Diamond.
Inclusion: A clarity characteristic found within
a diamond. Most inclusions were created when the gem
first formed in the earth.
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 Holes: One of the few man-made
inclusions that can occur inside a diamond. Why on earth
would anyone want to drill holes into a perfectly good
diamond? It may seem counter-intuitive, but drilling
this type of hole into a diamond can actually raise its
clarity grade. In some diamonds, the clarity grade may
be determined mainly by the presence of just one or two
dark included crystals in a diamond that is otherwise
relatively free of inclusions. In certain circumstances,
the diamond cutter will decide to use a procedure to
remove the dark inclusions and, hopefully, increase the
clarity of the diamond.
Loupe: Magnifying glass usually of 10X
magnification.
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.
Naturals:
This is a small piece of the original rough diamond's
exterior which was left on the polished diamond. These
are blemishes, but they might also be considered as a
mark of expert cutting; the occurrence of a natural
reflects the cutter's skill to design a stunning
polished gem, while still keeping as much of the
original diamonds weight as possible. Many times,
naturals do not affect the clarity rating. In most
cases, they are invisible to the bare eye.
Needle:
These look like exceptionally slight minute needles even
under a microscope.
Nick: A notch near the girdle or a facet edge.
Off-Make: A poorly proportioned Diamond.
Pavilion:
The pavilion is the piece of the diamond that lies right
under 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: A unit of measurement used to describe the
weight of diamonds. One point is equivalent to
one-hundredth of a carat.
Polish Mark: Surface clouding caused by excessive
heat (also called burn mark, or burned facet), or uneven
polished surface resulting from structural
irregularities.
Polish: Refers to any blemishes on the surface of
the diamond which are not significant enough to affect
the clarity grade of the diamond. Examples of blemishes
that might be considered as 'polish' characteristics are
faint polishing lines and small surface nicks or
scratches. Polish is regarded as an indicator of the
quality of as diamond's cut; it is graded as either
Ideal, Excellent, Very Good, Good, Fair or Poor.
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.
Semi-mount: A jewelry setting that has the side
stones already mounted, but which contains an empty set
of prongs which are intended to mount a diamond center
stone that the customer selects separately.
Single-cut: A very small round diamond with only
16 or 17 facets, instead of the normal 57 or 58 facets
of a full cut round brilliant. Single cuts are
occasionally used for pavé jewelry and other jewelry
that utilizes numerous small diamonds set closely
together.
Spread stone: A Diamond with a large table and a
thin crown height.
Step Cut: One of three styles of faceting arrangements.
In this type of arrangement (named because its broad,
flat planes resemble stair steps), there are three
concentric rows of facets arranged around the table and,
on the pavilion, there are three concentric rows
arranged around the culet. Other styles of faceting
arrangements include the brilliant cut (in which all
facets radiate out from the center of the diamond toward
its outer edges) and the mixed cut (in which either the
crown or pavilion of a diamond is cut as a brilliant
cut, and the other part of the diamond is cut as a step
cut).
Surface Graining: Surface indication of
structural irregularity. May resemble faint facet
junction lines, or cause a grooved or wavy surface,
often cross facet junctions.
Symmetry: Refers to variations in a diamond's
symmetry. The small variations can include misalignment
of facets or facets that fail to point correctly to the
girdle (this misalignment is completely undetectable to
the naked eye). Symmetry is regarded as an indicator of
the quality of as diamond's cut; it is graded as either
Ideal, Excellent, Very Good, Good, Fair or Poor.
Table percentage: The value which represents how
the diameter of the table facet compares to the diameter
of the entire diamond. So, a diamond with a 60% table
has a table which is 60% as wide as the diamond's
outline. For a round diamond, gemologists calculate
table percentage by dividing the diameter of the table,
which is measured in millimeters (this millimeter
measurement does not appear on diamond grading reports)
by the average girdle diameter (an average of the first
two millimeter measurements on the top left-hand side of
a diamond grading report). For a fancy shape diamond,
table percentage is calculated by dividing the width of
the table, at the widest part of the diamond, by the
millimeter width of the entire stone (this total width
measurement is the second of the three millimeter values
in the top left-hand corner of the diamond grading
report. Contrary to popular misconception, having a
small table percentage (53% to 57%) does not make a
round diamond any more brilliant than a diamond with a
larger table.
Table: The flat facet on the top of the diamond.
It is the largest facet on a cut diamond.
Tone: A color's position on a colorless-to-black
scale.
Treated Diamonds: A diamond with a body color
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
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