Cut
The Cut, or "make" of a diamond is the only factor of the 4C's that man can control. It is also the single most important attribute that affects its beauty and scintillation. A properly cut diamond will have facets placed in a precise geometric relation to each other. It should be neither too deep or too shallow. The "culet", or point, should be in the exact center of the bottom of the diamond. Excellent polishing and symmetry are also crucial in order for light entering the diamond to be reflected back as brilliance. If these proportions are compromised, the beauty, brilliance and value of the diamond is affected.
"Off-makes" can reduce the value of a diamond by 25% or more. Well-cut diamonds fall into precise guidelines that have been determined over many years by diamond authorities such as GIA and AGS.
Inferior Cut
Most diamonds are "spread" in their cutting to retain maximum weight from the original rough. A heavier diamond will result, but at a dramatic sacrifice of potential fire and brilliance.
Well Cut
Light entering the diamond reflects internally from facet to facet and is reflected back through the top ONLY, creating maximum brilliance.
Too Deep
When a diamond is cut too deep, light leaks out of the bottom, brilliance is lost and the center of the diamond will appear to be dark.
Too Shallow
When a diamond is cut too shallow, light leaks out of the bottom, brilliance is lost and the diamond appears watery, glassy and dark.
Color
Although most gem-quality diamonds appear colorless to the untrained eye, there are subtle differences in shade. Diamonds with no traces of body color are extremely rare and very costly. A diamond's color is determined by a trained professional who compares the color to a diamond in a "Master Set" whose color has been predetermined by an independent authority such as the Gemological Institute of America (GIA).
Clarity
All diamonds will have inclusions (crystals, feathers, carbon, etc.) under enough magnification. The diamond industry has defined the standard as 10X magnification. The magnification should not be lower for accurate grading purposes.
The clarity of a diamond is determined by the position, color, number, nature and size of the inclusions apparent under 10X magnification. The clarity of the diamond can vary from Flawess (exceedingly rare) to 13 (heavily included). While not all inclusions will affect the sparkle and beauty of a diamond, they do affect its value and price.
Carat Weight
The weight of a diamond is measured in carats. One carat is divided into 100 parts called "points". A stone that is 50 "points" is 1/2 carat, or .50ct. The value of two diamonds of the same weight can vary greatly depending on the other 3C's: Cut, Color, and Clarity. Additionally, two diamonds of equal weight can appear to be different sizes. This is due to variations in Cut.
