Diamond Cut and Shape

The term “cut” can mean many things. In the jewelry industry, it is used to describe the shape, cutting style, proportions and finish of a diamond. Diamonds can be cut into almost any shape (see the most popular shapes in the image below), such as a round brilliant cut or a princess cut. However, at 14 Karat, when we typically discuss the cut of a diamond we are referring to how well the diamond cutter did their job. Questions regarding the physical faceting, symmetry and polishing are answered when discussing the “cut” of a diamond.

diamond and gemstone shapes

A well cut diamond will return more light to the viewer and appear to be much brighter and more brilliant than a diamond that has been poorly cut. Unfortunately cut is the one factor that most people know nothing about and some jewelers may not discuss it in detail.

At 14 Karat we rely on the Gemological Institute of America (GIA) grading system for cut diagnostics just as we do for color, clarity and carat weight.

The system is based on 7 components divided into two categories: Face Up Appearance and Design/Craftsmanship. Face Up Appearance takes into account a diamond’s brightness, fire and scintillation. The Design/Craftsmanship category is based around a diamonds weight ratio, durability, polish and symmetry.

Brightness is primarily impacted by a diamonds cut and is the visual effect of white light internally and externally. A well cut diamond can be brighter than one with a higher color grade!

Fire is the visual effect of the white light being separated into colored light (like a rainbow).

Scintillation is the difference between light and dark, and the sparkle that results as the diamond is turned or the viewer moves. Sometimes people will refer to this as the “flash” they receive when moving a diamond back in forth in light.

Polish of a diamond is important because it is one of the “finish” grades along with symmetry. When grading polish, the grader will look for minor blemishes on the diamond caused by excessive heat during cutting, abraded culets and facet junctions. Polishing lines may also be present which are caused by extremely small pieces of diamond being dragged across the stone during cutting. At 14 Karat we strive to have all our round diamonds earn a “Very Good” or “Excellent” rating from GIA. In the fancy shapes we insist on at least a “Good” or higher rating. .

Symmetry does not refer to how “round” a diamond is. Instead it refers to how well the diamond cutter was able to align all the facet junctions on a diamond. The degree of inaccuracy is measured and used to calculate the symmetry grade. A diamond that is extremely accurately aligned will transmit and use light much more efficiently therefore generate more light to the viewer. Symmetry is an extremely important factor when determining the cut grade on a diamond as it shines a light on how well the cutter actually was able to transform the stone. As with polish, we are extremely particular and a “Very Good” or “Excellent” grade is the only grade we’ll accept on our round diamonds. We will not sell any diamond with anything less than a “Good” rating.

After taking in all of these factors, GIA gives the diamond an overall cut grade. It should be noted that at this time GIA only gives a cut grade rating to round brilliant cut diamonds. They have not released any data at this time concerning princess cuts or the other fancy shapes.

The top cut grade in a round diamond that you can purchase at this time is the “Triple EX” grade diamond. These diamonds have an overall cut grade of “Excellent”, a polish rating of “Excellent” and a symmetry rating of “Excellent”. These diamonds make up a fraction of round diamonds cut and can command as much as 8-12% more than a non-triple EX diamond. For those who want the best possible, this is it! GIA does not use the term “Ideal Cut” to refer to any round brilliant cut diamond.

14 Karat recommendation on CUT AND SHAPE

With round diamonds we recommend that the diamond achieve a “Very Good” or “Excellent” overall cut grade. With princess cut and other fancy shapes, a rating of at least “Good” or higher is mandatory on polish and symmetry, with “Very Good” being more common. At 14 Karat we are very particular with the overall cut grade of each diamond that leaves our store. We do not buy massive bulk parcels of diamonds but instead “cherry pick” those that meet our expectations. We pay a higher price for doing business with our suppliers this way, but it provides you, the customer, with the highest quality diamond. In addition, we always stand by our pledge to find exactly what you are looking for at no additional price.