What is the "CUT" of a diamond and why should you know it?
Of the 4 C's, cut is the most important.
Proper cutting of the rough diamond ensures that the ideal proportions are achieved. The accurate placement of each surface facet is essential to its beauty and value. The slightest error can create a substantial difference in the stone's brilliance. A diamond is nothing more than a prism that "refracts" or bends light rays. Correct proportioning is the key to unlocking a diamond's inner beauty.
If cut correctly, light enters through the top or "table" of the diamond and passes through to the lower portion called the pavilion until it strikes the pavilion facets. Here it is reflected back out through the top of the stone or it refracts from facet to facet and then it comes back through the top. It is this refraction of light and the unleashing of the spectrum that give a diamond its dispersion or fire, we call it in-short, it's life. A diamond which is cut too deep allows light to pass through the sides of the lower part of the diamond. A diamond which is cut too shallow allows light to pass through the bottom of the pavilion. The particular angles and finish of any diamond are what determine its ability to handle light, which leads to brilliance. .
What are the "cuts"
A well-cut diamond reflects light back to the eye evenly in the face-up position, with no dark areas. Dark or 'dead' areas are due to poor cutting, and should not be confused with the faint "bow-ties" which are typical of fancy shapes; in the case of fancy shapes, bow-ties are where the main brilliance and life of the diamond are least apparent.
As you can see from the illustrations above, when a diamond is well-cut (either a fine cut or an Ideal cut), light enters through the crown or top portion of the diamond and travels all the way to the pavilion where it reflects from one side to the other - intensifying in the mirror-like facets as it travels - before reflecting back out of the diamond through the crown and to the observer's eye.
This brightness that seems to come from the very heart of a diamond is known as brilliance. It is the effect that makes diamonds unique among all other gemstones. While other gemstones also display brilliance, none have the power to equal the extent of diamond's light-reflecting power (also what we like to call Bling).In a poorly cut diamond, however, the light that enters through the crown reaches the pavilion facets and then 'leaks' out from the sides or bottom of the diamond rather than reflecting back to the eye.
The illustrations above show how light behaves in different cuts of diamond. Note how the light 'leaks' out of the bottom and sides of diamonds that are too deep or too shallow. Well-made diamonds such as Ideal cuts and other fine cuts of diamond return light back to the eye, through the table, for maximum brilliance.
FINSH- Refers to the qualities imparted to a diamond by the skill of the diamond cutter. The term "finish" covers every aspect of a diamond's appearance that is not a result of the diamond's inherent nature when it comes out of the ground. The execution of the diamond's design, the precision of its cutting details, and the quality of its polish are all a consideration when a gemologist is grading finish. If you examine a diamond's grading report, you will see its finish graded according to two separate categories: polish and symmetry.
POLISH - Refers to any blemishes on the surface of the diamond that are not significant enough to affect the clarity grade of the diamond. Examples of blemishes that might be considered as 'polish' characteristics are faint polishing lines and small surface nicks or scratches.
SYMMETRY - Refers to variations in a diamond's symmetry. The small variations can include misalignment of facets or facets that fail to point correctly to the girdle (this misalignment is completely undetectable to the naked eye). Major symmetry problems are often seen in diamonds graded as Fair or Poor; they can include severe misalignment of facets, a noticeably off-center table or culet, a noticeably 'wavy' girdle, or a table which is noticeably not parallel to the girdle. In this technological and mechanized age, diamond cutting is still done by hand, not by machine. Professional cutting requires knowledge of the stone, a precise touch and flawless judgment.
Diamond cuts are broadly graded as Ideal, Excellent, Very Good, Good, Fair or Poor.
Excellent and Very Good diamonds are true works of art-perfect examples of the beauty and brilliance that a skilled cutter can impart to an already beautiful gem. Good diamonds are also a credit to the cutter's skill; though there are minor finish or symmetry characteristics in such diamonds, they are undetectable to the naked eye.
Keep in mind that most of the 'facts' that you hear about diamonds are really just the opinions and preference of one party or another. Different jewelers have different theories on what makes a diamond beautiful; they market these ideas to customers in order to create the sense of a unique brand of diamond that their customers can feel comfortable with. These theories are not necessarily 'wrong,' but they are also not the only theories that are 'right'. Whenever you see a chart that says the a diamond should be between x% and y% to be beautiful, keep in mind that these boundaries are merely intended as rough guidelines for consumers; you do not automatically risk choosing between a 'good' diamond or a 'bad' diamond in you choose something that lays outside these parameters. These ranges represent only an approximation of the average beautiful diamond. Ultimately, it is up to you to do your homework, look at a few diamonds and get to know your own personal tastes before you decide to buy. Then relax and trust your own instincts and the excellent quality of diamonds at Sawyers.