Understanding Diamond Clarity

The clarity of a diamond is a part of the four c’s, which determines the value of a diamond. A diamond’s clarity is defined as the measure of internal defects of a diamond, which are commonly known as inclusions.

Inclusions are defined as any foreign material, another diamond, or structural imperfections, such as small cracks that appear cloudy. The number of inclusions, the size of inclusions, and the visibility of inclusions can all affect the relative clarity of a diamond. The Gemological Institute of America (GIA) developed multiple systems to grade a diamond’s clarity.

The GIA’s grading system is based on inclusions that are visible to a trained professional when a diamond is viewed under a 10x magnification. A high diamond clarity grade is rare, and only 20 percent of all diamonds that are mined have a clarity grade high enough for the diamond to be considered appropriate for gemstone use.

Of the 20 percent of diamonds considered for gemstone use, a major portion of them contains one or more visible inclusions. Eighty percent of all mined diamonds are relegated to industrial use. Diamonds without any visible inclusions are known as “eye-clean” and are often preferred by buyers. However, some visible inclusions can be hidden under the setting in a piece of jewelry.       

Most of the inclusions present in gem-quality diamonds don’t usually affect the diamond’s performance or structural integrity. Large clouds can affect a diamond’s ability to transmit and scatter light, and large cracks that are close to or breaking the surface can reduce a diamond’s resistance to fracture.

Diamonds are usually graded on a scale ranging from flawless to imperfect diamonds. The location of a flaw in relation to the diamond’s cut is very important. Some internal flaws are more noticeable when they are positioned in specific areas of the stone; other flaws may be more hidden and not so noticeable.

It is possible to enhance a diamond’s clarity using treatments, but the treatments may not be permanent. The two most popular treatments are the laser treatment technique and the fracture filling technique.

In the laser treatment technique, a laser is used to remove some of the diamond’s inclusions. However, expert jewelers will be able to see the trail that is left by the laser.

Fracture filling is one of the treatments that is not considered permanent. In the fracture filling treatment, tiny cracks are filled with a colorless substance. The treatments allow diamond lovers to own diamonds that appear to be of higher clarity than they actually are.

Treated diamonds will also cost less than untreated diamonds, and jewelers should always inform buyers about any treatments that have been performed on a diamond.

The surface defects of a diamond are called blemishes. Diamonds with higher clarity grades are rare, and are therefore more valued with “flawless” diamonds having the highest prices. However, some blemishes are considered to have some value, and are sometimes seen as unique identifying marks analogous to fingerprints. The fingerprints of the diamond may also be used to provide proof a diamond’s natural origin.            

Several types of inclusions and blemishes can affect a diamond’s clarity in varying degrees. Some features that are the result of diamond enhancement procedures, such as laser lines, are also considered inclusions and blemishes.

Some common inclusions are clouds, feathers, included crystals or minerals, knots, cavities, cleavage, bearding, and internal graining.

Common blemishes are polish lines, grain boundaries, naturals, scratches, nicks, and pits.

In the world of diamonds, a higher clarity rating does not mean a more beautiful stone. If inclusions are invisible to the naked eye, higher clarity will not usually improve the diamond’s appearance, and will only make the stone more rare and give it a higher price.

Diamonds with a clarity of S12 or higher will usually be the most beautiful and valued for many buyers.