When jewelers judge the quality of a diamond cut, or "make", they often rate "Cut" as the most important
of the diamond characteristics. The way a diamond is cut is primarily dependent upon the original
shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation
of the weight, and the popularity of certain shapes. Don't confuse a diamond's "cut" with its
"shape." Shape refers only to the outward appearance of the
diamond and not how it is faceted.

A diamonds cutting proportions, directly effects the refraction of light. In other words how well a diamond is
cut, has everything to do with how much light is refracted from a stone and
the degree of sparkle, scintillation and brilliance a diamond shows.

When a diamond has a high quality cut (ideal cut), incident light will enter the stone through the table and
crown, traveling toward the pavillion where it reflects from one side to the other before bouncing
back out of the diamond's table toward the observer's eye. The phenomenon is referred to as
"light return" which affects a diamond's brightness, brilliance, and dispersion.
Any light-leakage caused by poor symmetry and/or cut proportions
(off-make) will adversely affect the quality of light return.



The "Shallow Cut" and "Deep Cut" examples above show how light that enters through the table of a modern round
brilliant diamond reaches the pavillion facets and then leaks out from the side or bottom of the diamond
rather than reflecting back to the eye through the table. Less light reflected back to the eye means
less "Brilliance." In the "Ideal Cut" example, most of the light entering through the table is
reflected back towards the ovserver from the pavillion facets.

The proportion and symmetry of the cuts as well as the quality of the polish are factors in determining the overall
quality of the cut. A poorly cut diamond with facets cut just a few degrees from the optimal ratio will
result in a stone that lacks gemmy quality because the "brilliance" and "fire" of a diamond
largely depends on the angle of the facets in relation to each other.

The symmetry of a diamond is related to the overall geometry of the diamond. In other words, how well the diamond is
faceted. Where cutting proportions affects how much light is being returned to the eye, symmetry affects the
break up of that light (the spheres of light or sparkle and scintillation you see when you turn the
diamond). An example of poor symmetry would be poorly shaped facets, facets that do not
meet up at perfect points. Uneven girdle and misshaped tables. Cutting problems which
effect symmetry can occur during the faceting process, when one incorrect facet
angle can throw off the symmetry of the entire stone. See the chart
below for common problems...




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