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Blemish
- A clarity characteristic that occurs on the surface of a diamond,
which is an imperfection external to the diamond.
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.
Bruise
- An inclusion consisting of surface crumbling, often accompanied
by tiny, root like feathers.
C
Carat Weight - The metric carat, which equals 2 milligram, is
the standard unit of weight for diamonds and most other gems. If
other factors are equal, the more a diamond weighs, the more valuable
it will be.
Cavity
- An inclusion consisting of a large or deep opening in the diamond.
Certificate
- Laminated document by a gemological institute to describe a Diamond's
characteristics.
Chip
- A tiny piece missing, caused by normal wear and tear, or by cutting.
Clarity
- A diamond'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 determines the clarity grade.
Very few diamonds are flawless, that means, show no inclusions or
blemishes when examined by a skilled grader under 10X magnification.
If other factors are equal, flawless diamonds are most valuable.
Cloud
- A group of tiny white inclusions that result in a milky or cloudy
appearance.
Color
- Grading color in the normal range involves deciding how closely
a diamond's body color approaches colorlessness. Most diamonds have
at least a trace of yellow or brown body color. 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.
Crown Angle
- The angle at which a diamond's bezel facets (or, on emerald cuts,
the row of concentric facets) intersect the girdle plane. This gentle
slope of the facets that surround the table is what helps to create
the dispersion, or fire, in a diamond. White light entering at the
different angles is broken up into its spectral hues, creating a
beautiful play of color inside the diamond. The crown angle also
helps to enhance the brilliance of a diamond.
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 diamond. 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 diamond; the more successful
the cutter is in balancing these considerations, the more valuable
the diamond will be.
D
Depth - The height of a diamond from the culet to the table.
The depth is measured in millimeters.
Depth Percentage
- There are two different measurements of a diamond's depth - the
actual depth in millimeters and the depth percentage, which expresses
how deep the diamond is in comparison to how wide it is.
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.
E
Emerald Cut - A step cut, usually rectangular.
Excellent
Cut - A GIA and HRD-CGL grade for excellent cut and polish of
brilliants.
Extra Facet
- A facet placed without regard for symmetry and not required by
the cutting style.
Eye-Clean
- A term used in the jewelry industry to describe a diamond with
no blemishes or inclusions that are visible to the naked eye.
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