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FL |
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Flawless.
A flawless diamond is exceptionally
rare and shows no inclusions
or blemishes
under 10x magnification. |
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F
Color |
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Colorless.
Extremely minute traces of color
are visible only when compared
to a D or E colored diamond.
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Face-down |
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The
position of a diamond which
orients the pavilion or culet
towards the viewer. Diamonds
are usually graded face-down.
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Face-up |
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The
position of a diamond which
orients the table towards the
viewer. Diamonds are mounted
face-up and clarity graded face-up
as well. |
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Facet |
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A
flat, polished surface on the
crown,
pavilion
and sometimes girdle
of a polished gem. Some polished
diamonds also have a flat facet
at the bottom of the pavilion,
called the culet. |
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Fancy
Colored Diamonds |
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Naturally
colored yellow and brown diamonds
that exhibit color beyond the
Z
color range, or that exhibit
any other color such as pink,
blue, green, red and orange
face up. Fancy colored diamonds
are considered extremely rare.
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Fancy
Cut
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Any
gemstone shape other than round. |
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Feather (Ftr)
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A
white and feathery break in
a gemstone. |
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Fineness |
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A
measure of purity for precious
metal alloys.
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Finish |
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The
finish of a diamond is quality
of its polish,
the condition of its girdle,
and the precision of its cut.
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Fire |
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Also
called dispersion,
fire is the separation of white
light into spectral colors which
appear as flashes of color.
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Fisheye |
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A
fisheye is when a diamond has
a pavilion
depth of less than 40% and a
circular gray reflection of
all or part of the girdle appears
through the table when the stone
is face-up.
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Fluorescence |
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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.
EGL
refers to this as photoluminescence
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Four
C's |
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The
four C's are criteria used to
grade the quality of diamonds.
These include cut,
color,
clarity
and carat
weight. |
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