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Flaw
- An imperfection of a diamond.
Fluorescence
- The mostly bluish glow of a diamond in high ultraviolet lighting
conditions. Ratings: none, faint, slight, medium, strong blue. Strong
blue fluorescence may cause the diamond to appear oily in daylight.
Fracture
- A crack on the diamond's surface.
G
GIA - Gemological Institute of America. This institute provides
reliable diamond grading reports.
Girdle
- The outer edge or the widest part of the diamond forming a band
around the diamond.
Grain Center
- A small area of concentrated crystal structure distortion, usually
associated with pinpoints.
H
Hue - Pure, spectral (prismatic) color. Hues include gradations
and mixtures of red, organdy, yellow, green, blue, violet and purple.
I
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.
L
Loupe - Magnifying glass usually of 10X.
M
Marquise Cut - A type of fancy shape diamond, which is elongated
with points at each end.
N
Naturals - 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.
Needle
- A long, thin included crystal that looks like a tiny rod.
O
Oval Cut - A type of fancy shape diamond, which is essentially
an elongated version of a round cut.
P
Pavilion - The bottom part of the Diamond, below the girdle.
Pear Cut
- A type of fancy shape diamond that resembles a teardrop.
Pinpoints
- Very small 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
scrape surface.
Polish Mark
- Surface clouding caused by excessive heat (also called burn mark,
or burned facet), or uneven polished surface resulting from structural
irregularities.
Princess
Cut - A type of brilliant cut fancy shape that can be either
square or rectangular.
R
Radiant Cut - A type of brilliant cut fancy shape that resembles
a square or rectangle with the corners cut off.
S
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 Ideal, Excellent, Very Good,
Good, Fair or Poor.
T
Table - The flat facet on the top of the diamond. It is the
largest facet on a cut diamond.
Table Percentage
- The value that represents how the diameter of the table facet
compares to the diameter of the entire diamond.
Trillion
Cut - A type of brilliant fancy shape that is triangular.
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