5 Diamond Specs Besides the Famous "4 Cs"

Discover the additional aspects to grading diamonds.

diamond specs besides the 4 Cs

When shopping for a diamond, everyone is told to concentrate on the four Cs: cut, clarity, color, and carat. And that is important advice, as those aspects are crucial to the overall look of your diamond. For a brief overview: The cut both gives the diamond its shape and determines how much sparkle it reflects. Clarity marks if the stone is internally flawless, has visual inclusions, or inclusions only seen under magnification. Color is actually to indicate if the diamond is colorless, or at least close enough to appear so to the average eye. Then there’s carat, or the weight of the stone. Typically, that will also reveal the size facing up in a ring, but that can depend on the shape. For example, emerald-cut diamonds do not show as much carat size as round diamonds. While the four Cs are critical when selecting a stone, there are five additional aspects in diamonds that should be considered.

Girdle
This would be the outer edge of the diamond. The pertinent measurement for a girdle is thickness. Medium is considered the best ranking, as too thin increases the rick of chipping, while too thick will make the diamond look smaller. Then you’d be overpaying for the carat weight! Thin and slightly thick ratings will likely be okay, but it is probably best to avoid the more extreme sides. However, more unusual diamond shapes such as marquis, heart, and pear do better with a thicker girdle along the pointed edge in order to prevent chipping at weak spots. 

Polish
The result of the polish that the diamond cutter does, this rating is graded similar to clarity in concept, although it is a poor-excellent ranking similar to that of cut. Poorly polished diamonds may show defects on the surface, such as scuff marks. Excellent to good will not feature marks visible to the naked eye, although diamonds below .75 carats will likely not be visibly affected by anything graded as fair or above. 

Symmetry
Contrary to what one may think, a diamond with a lower symmetry rating may not be the cut of a poorly cut diamond. More likely, it is someone trying to salvage carat weight from a rough diamond. A diamond with less than an excellent grade may feature asymmetrical aspects such as an off center table or misaligned facets. 

Culet
Actually very common in antique stones, culets stopped being fashionable by midcentury when diamond cutting technology improved. The bottom of the diamond should end in a point, that is when there is no culet. Think of a sharpened pencil, and then think of what it looks like when the lead breaks. That flat edge would be the culet, and the larger it is, the more visible it is through the table of the diamond. Too large and the culet will appear almost as a black hole in the middle of the diamond, or at the very least, reduce the stone’s brilliance.

Fluorescence
This usually has a blue effect, so it can actually make lower color grade diamonds appear whiter. Fluorescence is still typically seen as a negative, largely because diamonds with a higher rating are sometimes seen as having a hazy or oily appearance. Fluorescence is measured by a UV light, but don’t think that means the glow effect will only show up under black light. After all, the sun has UV light as well, which is why you should always wear sunscreen!

Opening photo by Jay Lawrence Goldman Photography

Authored by: Emily Lasnier