If a diamond is rounded up too quickly in the fashioning process, the surface of
the girdle will lack the smoothness and waxy luster of a finely turned girdle. Consequently,
numerous minute, hairline fractures extend a short distance into the stone. A girdle
with this appearance is referred to as being “bearded” or “fuzzy.”
A clarity characteristic that occurs on the surface of a diamond. Though some blemishes
are inherent to the original rough diamond, such as an abrasion, natural, nick,
or scratch. most are the result of the environment the diamond has encountered since
it was unearthed.
The overall strength of a diamond’s light return, an average measured in the face-up
position. 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. 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.
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 is designed to maximize brilliance. Round diamonds,
ovals, radiants, princesses, hearts, marquises, and pears all fall within this category
A minute imperfection that breaks the surface of a diamond
On a diamond , a girdle that is cut, but unpolished.
The unit of weight by which a diamond is measured. One carat equals 200 milligrams,
or 0.2 grams. The word comes from the carob bean, whose consistent weight was used
in times past to measure gemstones.
An inaccurate term used by some people in the diamond 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.
A type of inclusion consisting of a large or deep opening in the diamond. It may
be cause by cleavage, by a blow, or may have been “pulled out” from the surface
during the polishing operation.
A curved break on a diamond that extends from a surface edge. (b) A small rose-cut
diamond or single-cut melee. (c) A cleavage piece of diamond that weighs less than
one carat. (d) A small, irregularly shaped diamond.
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).
A grouping of a number of extremely tiny inclusions that are too small to be distinguishable
from one another, even under magnification. The result is that, under a microscope,
this grouping often looks like a soft transparent cloud inside the diamond. Of course,
clouds cannot be seen with the naked eye. Usually, this sort of inclusion does not
significantly impact a diamond's clarity grade.
A system of grading diamond colors based on their colorlessness (for white diamonds)
or their spectral hue, depth of color and purity of color (for fancy color diamonds).
For white diamonds, use a grading system which runs from D (totally colorless) to
Z (light yellow).
The upper portion of a cut gemstone, which lies the girdle. The crown consists of
a table facet surrounded by either star and bezel facets (on round diamonds and
most fancy cuts) or concentric rows of facets reaching from the table to the girdle
(on emerald cuts and other step cuts).
Crown Angle is the angle measured between the girdle plane and the bezel facets.
Along with the table size, the crown angle helps determine the amount of dispersion
displayed by the diamond.
Crown Height is the millimeter distance the table is above the girdle.
Crown Height Percentage:
Crown Height Percentage is the crown height expressed as a percentage of the average
Crystal is a type of inclusion where a mineral deposit is trapped inside the diamond.
A tiny flat facet that diamond cutters sometimes add at the bottom of a diamond's
pavilion. Its purpose is to protect the tip of the pavilion from being chipped or
damaged. Once a diamond is set in jewelry, though, the setting itself generally
provides the pavilion with sufficient protection from impact or wear. Most modern
shapes have either no culet at all, or a small or very small culet.
This refers both to the proportions and finish of a polished diamond. As one of
"the Four Cs" of diamond value, it is the only man-made contribution to a diamond's
beauty and value.
Cutting styles are different than diamond shapes. The simplest and most common way
to explain cutting style is to categorize it into the following three basic types:
Step-cut, Brilliant-cut and Mixed-cut.
The height of a diamond from the culet to the table. The depth is measured in millimeters.
On a diamond grading report, you will see two different measurements of the diamond's
depth-the actual depth in millimeters (under "measurements" at the of the report)
and the depth percentage, which expresses how deep the diamond is in comparison
to how wide it is. This depth percentage of a diamond is important to its brilliance
and value, but it only tells part of the story. Where that depth lies is equally
important to the diamond's beauty; specifically, the pavilion should be just deep
enough to allow light to bounce around inside the diamond and be reflecting out
to the eye at the proper angle.
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).
Diamond Cutting is the method by which a rough diamond that has been mined from
the earth is shaped into a finished, faceted stone.
Diamond Gauge is an instrument that is used to measure a diamond’s length, width
and depth in millimeters.
Arranged around the table facet on the crown are several smaller facets (bezel and
star facets) angled downward at varying degrees. These facets, and the angles at
which they are cut, have been skillfully designed to break up white light as it
hits the surface, separating it into its component spectral colors (for example,
red, blue and green). This effect, which appears as a play of small flashes of color
across the surface of the diamond as it is tilted, is what we refer to as the diamond's
dispersion (also called "fire").
A square or rectangular-shaped diamond with cut corners. On the crown, there are
three concentric rows of facets arranged around the table and, on the pavilion,
there are three concentric rows arranged around the culet. This type of cut is also
known as a Step Cut because its broad, flat planes resemble stair steps.
An term used in the diamond industry to describe a diamond with no blemishes or
inclusions that are visible to the naked eye (i.e. a human eye which is not aided
by magnifying devices such as a loupe or a microscope).
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). The shape, quantity, and arrangement of these facets will
differ slightly among other fancy shapes.
Any diamond shape other than round – e.g. princess cut, marquise, square, emerald,
oval, heart and pear.
These are small fractures in a diamond. They are usually caused by the tremendous
stress that the diamond suffered while it was growing underground. In some cases
the feather both begins and ends within the diamond's surface and, in other cases,
the feather begins inside the diamond and extends to the surface. When viewed under
magnification, some feathers are transparent and others have a light white appearance
The word finish is used to describe the exterior of the diamond. If a diamond is
well polished, it has a very good finish.
Often a term used instead of “dispersion,” it is the variety and intensity of rainbow
colors seen when light is reflected from a diamond.
When exposed to ultraviolet light, a diamond may exhibit a more whitish, yellowish
or bluish tint, which may imply that the diamond has a property called fluorescence.
The untrained eye can rarely see the effects of fluorescence. Diamond grading reports
often state whether a diamond has fluorescent properties. Fluorescence is not considered
a grading factor, only a characteristic of that particular diamond.
The girdle is the outermost edge of the diamond between the crown and the pavilion.The
girdle is not graded, but rather it is described by its appearance at its thinnest
and thickest points.
When a diamond has a pavilion that is too shallow or flat, the girdle is seen reflected
in the table.
A diamond’s outermost edge is also known as the girdle. Its thickness is measured
as a percentage of the diameter (e.g. thin = 1.0%, medium = 3.0%, thick = 4.0% etc…)
or quoted as words (such as Thick or Thin). On a grading report, the finish of the
girdle will also be stated and listed as one of the following: polished, faceted
A clarity characteristic found within a diamond. Most inclusions were created when
the gem first formed in the earth. A general term used to refer to any external
blemish or internal inclusion or flaw on or in a fashioned diamond; e.g., a feather,
carbon spot, knot, fissure, scratch, natural, etc. The term “flaw” and “imperfection”
are usually used interchangeably.
Small parts of the original rough diamond's surface which are left on the polished
diamond, frequently on or near the girdle. While these are blemishes, they might
also be regarded as a sign of skilled cutting; the presence of a natural reflects
the cutter's ability to design a beautiful polished gem, while still retaining as
much of the original crystal's weight as possible. In many cases, naturals do not
affect the clarity grade. In most cases, they are undetectable to the naked eye.
Another type of natural is the Indented Natural; in this case, the portion
of the original rough diamond's surface which is left on the polished diamond dips
slightly inward, creating an indentation. Usually, the cutter makes an effort to
cut the polished diamond so that the indented natural will be confined to either
the girdle or the pavilion (making it undetectable to the naked eye in the face-up
A culet that, due to differences in the angles of the opposite pavilion facets,
is off center with respect to the girdle outline.
A term that is sometimes used to refer to the table on a spread, or swindled, diamond.
To some, any table diameter of 60% or more of the girdle diameter is open; to others,
open means 65% or more.
A type of fancy shape diamond which is essentially an elongated version of a round
Bottom portion of the stone, under the girdle, measuring to the culet.
Pavilion Angle is the angle measured between the girdle and the pavilion main facets.
Pear Shape diamond or gemstone is shaped like a teardrop, rounded on one end and
pointed on the other.
A unit of measurement used to describe the weight of diamonds. One point is equivalent
to one- hundredth of a carat.
A type of brilliant cut fancy shape that can be either square or rectangular.
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.
The step cut has rows of facets that resemble the steps of a staircase. The emerald
cut and the baguette are examples of the step cut.
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.
The flat facet on the of the diamond. It is the largest facet on a cut diamond.
The large facet that caps the crown of a faceted gemstone. In the standard round
brilliant, it is octagonal in shape and is bounded by eight star facets.
Table Percentage is the value which represents how the diameter of the table facet
compares to the diameter of the entire diamond.
A type of brilliant fancy shape that is triangular.