The following is intended to provide some basic information that may assist you in making an informed jewelry purchase. Diamonds are graded based on four characteristics known as the 4Cs.
Cut
Cut refers to proportions, symmetry and finish of a diamond. It also refers to the shape outline of the diamond (i.e. round, oval, marquise, pear, princess, etc.)
The modern round brilliant cut contains 58 facets.
Proportion and finish are responsible for Brilliancy (return of white light from within the diamond), Dispersion (break up of white light into spectral colors as it exits from the diamond - also called "fire"), and Scintillation (reflection of white light from facets). The degree of Fire and Brilliance of a diamond display depends primarily on how well the stone has been proportioned.
An ideal cut diamond is a round brilliant cut that is fashioned with a very specific set of proportions, which have been proven to yield the best balance of brilliancy and dispersion. Ironically only a small proportion of diamonds are cut to these proportions because it requires greater loss of the original diamond crystal.
For a more detailed description of cut, please see the American Gem Society's web page.
Color
Color refers to the body color of the diamond. Most diamonds have a slight trace of yellow, brown or gray. With the exception of naturally "Fancy Color" diamonds, the more colorless a diamond is, the greater is its value.
GIA GRADE DESCRIPTION
GIA grading scale for colorless to light ranges from D to Z. Diamonds range from colorless, which is the rarest and most valuable, to yellowish, with a spectrum of shadings in between.
D E F |
G H I J |
K L M |
N O P Q R |
S T U V W X Y Z |
Colorless |
Near Colorless |
Faint Yellow |
Very Faint Yellow |
Light Yellow |
Fancy color diamonds can be naturally colored or treated.
Diamonds of natural color are also rare and can be high in value. Colors might include purple-red, red, blue, pink, green, yellow, champagne.
For a more detailed description of color, please see the American Gem Society's web page.
Clarity
Clarity refers to Inclusions (internal characteristics) or Blemishes (external characteristics) observed under 10X magnification. The Clarity is based on the size, nature, number, position, and color of the characteristics. The greater the Clarity of the diamond the more rare the stone is and therefore the greater the value.
GIA scale ranges from Flawless to Imperfect (see below for description)
Carat
Metric carat equals 0.20 (one fifth) of a gram. Point is used to refer to proportion of a carat (one point equals 1/100 of a carat; 50 points equal 0.50 ct). Because of its relative rarity, the larger the stone the greater the price per carat (all other things equal).
For a more detailed description of carat, please see the American Gem Society's web page.
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