Cut, A Diamond’s Sparkle


In its natural state, a diamond’s beauty is generally well-concealed, but once cut, its brilliance is unlocked. Its value and beauty comes from reflecting the maximum amount of light possible through its main facets. In a well-cut diamond, the facets reflect light off one another and disperse it through the top. A diamond cut too deep or too shallow causes light to bounce out sideways or through the bottom. A diamond’s face-up appearance (brightness, fire and scintillation), design (weight ratio and durability) and craftsmanship (polish and symmetry) are considered when GIA evaluates cut. The symmetry of the diamond and the polish are rated separately on the lab reports. Symmetry refers to how evenly placed are the facets, and polish is how clear the diamond’s surface is from streaks and graining (only seen under a microscope). 

The GIA cut scales ranges from excellent to poor. GIA provides a cut quality grade for the standard round brilliant cut diamonds that fall in the GIA D to Z color range.

Color, A Diamond’s Whiteness

Although many diamonds appear to be colorless, most contain tints of yellow or brown in varying degrees. The color gradations, from “colorless” to “light yellow,” are often barely perceptible to the eye but can translate into thousands of dollars per carat. The highest color rating among white diamonds is D. Nature makes diamonds in all colors of the rainbow like yellow, pink and blue. These fancy color diamonds are very rare and are collectors’ items.

GIA Color Scale


Fluorescence is caused by the presence of nitrogen in the diamond. Its effect is usually negligible but it merits a separate rating in lab reports. Diamonds with fluorescence emit a soft glow when exposed to ultraviolet light. A rating of strong blue fluorescence can make the diamond appear bluish in tint, and a very small percentage will appear hazy or oily. Fluorescence does not affect the structure of a diamond, and is not a factor in determining color or clarity grades. Diamonds with medium, strong, or very strong fluorescence are usually highly discounted.


Clarity, A Diamond’s Purity

Microscopic crystals or minerals, called inclusions, are inside almost every diamond and contributes to its uniqueness. A diamond is “flawless” – the highest quality grade – if it free of inclusions (as well as surface marking) under 10–power magnification. Flawless diamonds are extremely rare. The number, size and position of inclusions affect the value of the diamond. Without high manifestation, however, you may never see the tiny inclusions in the diamonds you select. For rings, consumers often choose VS (Very Slightly Included) of SI ( Slightly Included) Clarity stones.

(Diamond chart is for comparing promotional differences in sizes, the actual stone may vary due to different computer screen resolutions and settings.)

Carat Weight, A Diamond’s Size

Size is the most visible factor that determines the value of a diamond simply because large stones are rarer than small ones. A diamond’s weight is measured in “carats” One carat contains 100 “points,” so a diamond can be described as either 150–points or 1.5 carats. Diamond chart is for comparing promotional differences in sizes. The actual size of the stone may vary due to different computer screen resolutions and settings.

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