Key Factors for Determining the Value of a Diamond
The key to a diamond’s value is its rarity, and no two diamonds are alike. Rarity is determined by a diamond’s unique characteristics as measured by the Four Cs: Cut, Color, Clarity and Carat Weight.
Color
The Gemological Institute of America (GIA) Color Scale extends from D (colorless) to Z (light yellow or brown). Although many people think of gem quality diamonds as color-less, truly colorless diamonds are actually very rare. Most diamonds used in jewelry are nearly colorless with tints of yellow, brown, or gray. 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 a color is.
GIA Color Scale
Clarity
The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3. Because diamonds form under tremendous heat and pressure, it is extremely rare to find a diamond that lacks any internal characteristics (called inclusions) and external blemishes. These characteristics are a byproduct of its formation
VVS2 VS2
SI2 I2
Cut
Cut refers to the face up shape of a diamond; for example round, princess, oval, pear, etc. The GIA Cut grading scale is used with round brilliant diamonds only, and ranges from Excellent to Poor.
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 magnificent display of three attributes. Brightness is the combination of all white light reflecting from the surface and interior of a diamond. Fire describes the scattering of light into its spectral or rainbow colors. Scintillation describes the flashes of light you see when the diamond, the light, or the observer moves.
A polished diamond’s proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with fine proportions, symmetry, and polish optimize their interaction with light, and have increased brightness, fire, and scintillation.
Carat: Diamond weights are measured in “carats.” One carat equals 1/142nd of an ounce, or 1/5th of a gram. In other words… there are 142 carats in 1 ounce and 5 carats in 1 gram.
The word “carat” comes from the ancient practice in India (where diamonds were first discovered and traded) of measuring diamond weights with the one thing in nature that is both small and the most consistent in weight — the carob seed. Thus the name “carat” evolved in the English language, which is still equivalent to approximately the weight of one carob bean.
Points
You also may have heard jewelers talking about “points” when discussing diamond sizes. This does not refer to the number facets on a diamond, but rather to its weight. Just like one pound is divided into 16 ounces, one carat is divided into 100 points — so each point is 1/100th of a carat. A “10-point” diamond weighs 1/10th of a carat, and a 50-point stone weighs one-half carat.
