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Diamond Cut

The Four Cs: CUT

Cut is the most important of all the Cs of a diamond for cut define a diamond’s character and consequently the diamond’s shine and sparkle for which diamonds are so popular. A well cut diamond will result in most important attributes of a diamond: brightness, fire and scintillation.

Brightness – also known as brilliance is referred to as the white light that is reflected back to the viewer from the surface and inside of a diamond.

Fire – is referred to as the coloured light return from a diamond. Those colorful flashes that you see coming of a diamond in different lighting environment is what is known as fire.

Scintillation – described as the on/off flashes of light and contrasting dark areas one observes when the diamond is moved or the viewer moves.

Light Performance:

When a light enters a diamond its either reflected off as white light return (brilliance) or coloured light return (Fire). However if a diamond is not well cut all the the light entering the diamond may not be reflected back to the viewer and may leak from the pavilion of the diamond. It is extremely important to select a diamond that is nicely made so that diamond does what it’s supposed to do.

Understanding & Grading Cut:

The GIA grades the cut on diamond’s proportions, it’s finish that consists of polish and it’s symmetry. Let’s look at them one by one:

Proportions: The most important of the cut determinant. A diamond’s proportions are based on it’s girdle outline, table size, crown angle, girdle thickness, pavilion depth, total depth, culet size and length to width ratio. GIA has devised tables on the basis of the research they have conducted over the period of several years and gathered data on what proportions results in a diamond that is most appealing to the viewer, less appealing to the viewer and so on and has come up with proportion values to assign cut grades. The diamond is given a cut grade according to those values. The proportions are graded on the scale of Excellent to Poor. Excellent proportion diamonds are those that reflect the most light to the viewer and perform the best. However this proportion set is very large and may include less performers at the either side of the scale. Swanstar prides its self in stocking some of the most strictly cut diamonds to exacting standards to reflect most light back to the viewer. Our super ideal heart & arrows rounds are the best performing diamonds in the world along with the romantic attachment of Hearts & Arrows.

Finish – Polish & Symmetry: A diamond’s finish consists of it’s polish and it’s symmetry.

Polish: Polish refers to the overall condition of the diamond’s facet surface. Polish characteristics such as polish lines, burn marks, rough girdle etc affects the polish grade of a diamond when visible under 10x magnification. The Polish is graded on the scale of Excellent to Poor just like the proportion. A diamond with excellent polish means none or very few hard to find polish lines or tiny nicks on the diamond facet surface. A polish rating of good might show noticeable white polish lines and few burned facets. Obvious features will take the diamond’s polish grade to Fair and when those characteristics start to hamper the diamond’s transparency and performance it would be categorized in the poor grade.

Symmetry:  Symmetrical diamond has superior and balanced display of brilliance, fire and scintillation compared to less symmetrical diamonds. Symmetry variations may include off centre table or culet, out of round girdle, facets that don’t meet at their junctions properly, misaligned facets, out of shape table, misshapen facets, extra facets and an uneven outline. Very few diamonds have perfect symmetry however the most conscientiously cut diamond will have extremely few or no symmetry variations. This results in higher performance and light return. Our hearts & arrows & ideal cut grade diamonds have extremely slight to no symmetry variations and also have perfect optical symmetry that results in superior performing diamonds.

Hearts & Arrows:  Hearts & Arrows refers to the phenomenon shown by diamonds that are extremely well cut with perfect symmetry. 8 symmetrical arrows and 8 symmetrical hearts are visible in the diamonds crown and pavilion view when viewed through a hearts & arrows scope. These diamonds are cut to the most exacting standards as a slight variation in the proportions will not result in a perfect hearts & Arrow. For example lower girdle facets exceeding 77-78% will result in broken hearts, table exceeding 59-60% will result in pointy hearts, crown angle above 36 degrees and below 33.7 degree will not result in perfect arrows and so on. To achieve a hearts & arrows with impeccable light performance like our Signature collection Hearts & arrows the cutter has to cut a diamond within very specific parameters. This results in more rough diamond weight loss and thus these diamonds command a premium over their non-H&A and non-ideal counterparts.



Ideal Cut: Ideal cut diamonds like hearts & arrows are cut to the ideal proportions to reflect most light back to the viewer but lack the optical symmetry of a Hearts & Arrows diamond. While GIA does not give out an Ideal cut grade, the AGS (American Gems Society) recognizes the Ideal cut grade and has defined a set of ideal proportions. Our ideal cut diamonds are presented to customers with reflector images like ASET scope images and Idealscope images to describe the light performance of these diamonds.