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The Four C's
Every diamond is unique. Each reflects 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 1/5 of a gram in weight
For diamonds under a carat, each carat is divided into 100 points – similar to
pennies in a dollar. 0.75ct. = 75 points, ½ ct. = 50 points
Clarity: The GIA Clarity Scale includes eleven clarity grades ranging from
Flawless to I3. Given that diamonds form under tremendous heat and pressure,
internal and external characteristics are common. These characteristics help
gemologists separate natural diamonds from synthetics and simulants, and
identify individual stones.
There are two types of clarity characteristics: inclusions and blemishes – the
difference is based on their locations. Inclusions are enclosed within a diamond
while blemishes are confined to its surface.
Color: The GIA Color Scale extends from D (colorless) to Z (light yellow or
brown). Although many people think of gem quality diamonds as colorless, most
diamonds used in jewelry are nearly colorless with tints of yellow or brown.
Color grades are determined by comparing each diamond to a master set. Each
letter grade represents a range of color and is a measure of how noticeable the
color is.
Cut: The GIA Cut Scale ranges from Excellent to Poor. GIA provides a cut quality
grade for standard round brilliant diamonds that fall in the GIA D-to-Z color
range.
A polished diamond’s beauty lies in its complex relationship with light: how
light strikes the surface, how much enters the diamond, and how, and in what
form light returns to your eye.
The result is a display of three attributes. Brightness is the combination of
all white light reflecting from the surface and interior of a diamond. Fire is
the colored flashes that can be seen in a diamond. Scintillation describes the
sparkle of light you see in a diamond, and the overall pattern of bright and
dark areas when you look at a diamond face-up.
A polished diamond’s proportions affect its light performance, which in turn
affects its beauty and overall appeal. Diamonds with good proportions optimize
the interaction with light, and have good brilliance, fire, and scintillation.
The Design (weight ratio, durability) and Craftsmanship (polish, symmetry) of a
diamond also affect its cut quality, and are considered in determining a
diamond’s GIA Cut Grade.
Fluorescence: Many diamonds emit a visible light when exposed to ultraviolet
radiation. Although fluorescence is not a factor in determining color or clarity
grades, a description of its strength and color is provided on GIA Reports for
identification purposes.
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