Every diamond is unique, reflecting the story of its
arduous journey from deep inside the earth to a cherished object of
adornment. Yet all diamonds share certain features that allow us to
compare and evaluate them. These features are called the 4Cs.
CARAT WEIGHT:
One carat equals 0.2 grams. For diamonds under a carat, each carat is
divided into 100 points, similar to pennies in a dollar. For instance,
0.75ct. = 75 points and 1/2 ct. = 50 points.
CLARITY:
The GIA Clarity Scale includes eleven clarity grades ranging from
Flawless to I3. Because diamonds form under conditions of tremendous
heat and pressure, internal inclusions and external blemishes are
common and help gemologists identify individual stones. The Clarity
Scale also helps separate natural diamonds from synthetics and
simulants.
COLOR:
The GIA Color Scale extends from D (colorless) to Z (light yellow or
brown). Although many people think of diamonds as colorless, most
diamonds used in jewelry have subtle tints of yellow or brown. Each
letter grade represents a range of color and is a measure of the degree
of color within the diamond, all measured by comparing the diamond to a
set of master stones.
CUT:
A polished diamond's proportions affect the performance and interplay
of light which, in turn, affects its beauty and desirability.
Brightness is the combination of all white light reflecting from both
the surface and interior of a diamond. Fire describes the colored
flashes that can be seen in a diamond. And scintillation is the sparkle
of light you see and the overall pattern of bright and dark areas when
you look at a diamond face-up. The design and craftsmanship of a
diamond also affect its cut quality, and these factors are considered
in determining a diamond's GIA Excellent-to-Poor Cut Grade.
Many diamonds emit a visible light, called fluorescence, when exposed
to ultraviolet radiation.
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