Diamond Color & Clarity Enhancement: Types and Methods

Sharif Khan
Sharif Khan
Last Updated    EST 

Diamonds are among the most highly-priced gemstones on Earth. They are widely used as jewelry ornaments and industrial tools. Diamonds are among the highest demanded items because of their beauty and durability. However, colorless and flawless diamonds are extremely rare. Therefore, some diamond dealers enhance non-gem quality, highly included, and/or colored diamonds to improve their appearance. There are several processes to enhance the clarity and color of diamonds.

Check out this quick diamond-buying cheat sheet.

Clarity Enhancement

The clarity of diamonds refers to the degree of imperfections or inclusions embedded in a diamond. Inclusions can make a diamond look ugly for many reasons. These imperfections also interfere with the light passing through the diamond and creating its sparkly reflection. Looking closely at the diamond, you can see the edges where lights reflect as it passes through the stone. Inclusions lessen the brilliance of the diamond because it restricts the light from coming through. To hide these inclusions, diamond cutters are very careful in cutting the diamonds. Usually, they cut under the bezel facets or near the girdle to hide the inclusions.

To add market value to non-gem quality diamonds, several ways exist to enhance their clarity. Among the widely used processes are color enhancement, HPHT (high-pressure, high-temperature), laser drilling, and fracture filling.

Color Enhancements

One of the widely used processes to treat a diamond’s clarity is color enhancements. These include treating the diamond using a mask or coat to polish the diamond. In this process, the diamond is coated with the matched color; usually, a thin layer of industrial chemical or a durable plastic is used. Some jewelry manufacturers use synthetic diamonds to mask a tinted area, thus making the blemished diamond look like a colorless stone.

Subjecting Diamonds to HPHT

Another method to enhance the clarity of a diamond is by subjecting it to HPHT. HPHT is an industrial acronym that stands for high-pressure, high-temperature. During this process, the diamond, tainted or raw, is subject to very high pressure and very hot temperature in a laboratory to create a new colored gemstone. Diamonds that appear colorless, yellow, pink, green, and yellowish are subjected to this process to create their color effect. These color effects also treat the clarity of a diamond. When subjected to this treatment, the blemishes of diamonds are barely undetectable.

The color of a diamond treated under HPHT is permanent as they have been under acids, ultrasonic treatment, and high pressure and heat. Diamonds subject to HPHT are usually more polished because of surface oxidation. It restores the shininess of the diamond, giving it a gleam of new look. However, since it has been polished, there is a chance that the diamond will lose some of its weight.

Laser Drilling

Another common method to restore the clarity of a diamond is through laser drilling. This has been a widely used method since the early 1960s. Laser drilling cleans the dark (sometimes brown or colorless) marks inside the diamonds. These marks are usually made of other minerals that develop inside the stone. They can be graphite (which will become diamond in hundreds of years), sulfide, or iron.

During the laser drilling process, the laser is positioned directly at the location of the blemish. It should be precise to avoid destroying the gemstone. Laser drills are usually set at 1064 nm solid-state. The laser creates microscopic incisions to clean the imperfections. Once the laser treatment is complete, the treated diamond will be clearer.

However, some experts say laser drilling leaves empty spaces once the inclusions are removed. Like in any filled spaces, once a certain substance is removed, blank spaces are left. These spaces leave hollow tunnels inside the gemstone, damaging its durability. This is where the next process comes in– filling those empty spaces through fracture filling.

Fracture Filling

Once the diamond undergoes a treatment, especially a laser treatment, to remove blemishes inside, the process leaves an empty space. This makes the diamond more fragile and less durable. Some jewelry makers and collectors find treated diamonds impure and of lesser value. To take care of this concern, diamond collectors, jewelry makers, and those who are in the gem industry discovered a process to fill in those hollow spaces. This process is called fracture filling.

During the fracture-filling process, another diamond is inserted inside each space, thus, hiding the imperfect feathers or fractures of the gemstone. Aside from real diamonds, jewelers also use glasses and synthetic diamonds as fillings. This is an intricate and delicate process. It requires precision and skills in diamond cutting to master this type of filling.

Once the process is finished, it will be very hard to distinguish the filling in a diamond. However, a truly skilled diamond master or diamond grader can spot the difference. There are also several claims that diamonds that underwent fracture filling are not permanent and can be destroyed, especially when they are subjected to several cleaning and immense heat.

Laser drilling and fracture filling are among the widely used processes in the market today. Although there are numerous ways to identify a clear diamond from a treated one, it is still advisable to consult an expert on these stones when buying a piece of jewelry. There are magnifying glasses used in jewelry stores to prove that what they sell are real diamonds. Some grading companies can provide a certificate clarifying whether a diamond is treated.

How to find out if a diamond is enhanced in GIA reports?

Here is an illustration of how GIA addresses such enhancements, if any, in its grading reports for natural diamonds. Always pay close attention to the comments section.

First, GIA would put a star sign next to the clarity or color (whichever is enhanced), as shown below:

Color Enfacement GIA

Then, GIA would explain how the diamond is treated in the comments section as shown below:

Diamond Color Enhancement GIA

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