Cut height is the most important factor in a diamond's brilliance. Since it's all about light optics and the ideal angles to produce the maximum effect the cut is critical to the beauty of the diamond.
The Cut of a Diamond is the only property which is totally dependent on man. Although often overlooked, cut is actually one of the most important aspects to consider when choosing your diamond. A Diamond cutter analyzes the rough diamond, and has to determine how to extract the most beauty and most profit out of the rough stone.
The Round Brilliant :- Cut is designed to provide maximum optics for the brilliance and scintillation, making the light seem to sparkle and dance in the light.
The most common, and most "brilliant", diamond cut is the Brilliant Cut, a.k.a. the Round Cut, American Ideal Cut, or American Standard Cut.
The Marquise Cut :- Looks something like a football, when viewed straight down from the top. Some Marquise are cut too thin and suffer from a markedly dark center (commonly called the bow tie effect). This effect is eliminated by paying attention to the depth (want lower sixties) and the crown height (want close to 14%) The light passes through the back of the stone due to the criticality of the angles needed to reflect the stone being too steep.
Oval Cut :- Has an elliptical shape when viewed from the top.
For both the Oval, the ratio of the length to the width should be about 1.5:1. If it is much greater then that you will see a dark area. This is commonly called a bow tie effect, "undesirable". If the ratio is much less then 1.5:1, the stone looks like a misshapen round.
Pear Shape Cut :- The pear is another popular fancy cut it uses the base of a brilliant or round cut and extends it self to point , if well proportioned it gives a depth of scintillation to the point of the stone. A benefit in design if a longer look is required.
Emerald Cut :- The Ideal Emerald cut features additional extra facets strategically placed to dramatically improve light return and optical symmetry. This Emerald Cut Diamond retains the elegance of the traditional Emerald cut with dramatically improved brilliance.
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