Colorless diamonds are evaluated by a universally accepted scale (D-Z) developed by GIA to recognize and communicate the lack of body color in each stone. The scale starts with D representing a total lack of color or the whitest and goes to Z or the last designation on the scale, indicating a light yellow presence in the body color.
Many of these color levels are so subtle that only a trained eye can detect the difference from one letter to the next. However each color grade whether up or down has an impact on the diamond's price.
The most coveted diamond color is D-E-F indicating a total lack of body color in the diamond. However these natural occurrences are exceptionally rare. But diamonds with this color grade are more scintillating and exhibit exceptional fire and life, allowing the optimum light to pass through the stone and be reflected back to the eye.
The clarity grade establishes the internal and external natural flaws, properly referred to as inclusions. A diamond with no internal or external inclusions whatsoever is graded FL for Flawless and the most inclusions found on a graded diamond label it as I for Included.
The 6 main clarity grades are: FL-Flawless, IF-Internally Flawless, VVS-Very Very Slightly Included, VS-Very Slightly Included, SI-Slightly Included, and I-Included.
The number of inclusions, their size, color and placement on the stone all impact their beauty because they contribute how the diamond can handle reflected light. A few inclusions may not affect the beauty of a stone, but can make its price more affordable to the consumer.
The rarest of all diamond occurrences are those considered Flawless. Nature rarely produces a diamond crystal without some identifying natural inclusions. It's simply a bi-product of their growth to have some inclusions or flaws. A Flawless diamond is highly desired and its price reflects this.