Commonly Used Diamond Treatments


Loose Cushion Cut Diamond

Diamonds are formed naturally; hence they can vary much in quality. The difference in quality can also significantly affect the value of diamonds. If the stones have blemishes or inclusions, it can reduce its value. Hence, jewelers have developed many technologies over the years for improving the quality of diamonds. These treatments are usually used to enhance the clarity and the color of diamonds.

When buying diamonds, you have the right to know whether the diamonds you are buying are treated or not. Whether you choose a round brilliant diamond, loose emerald cut diamond, loose cushion cut diamond, or any other diamond, you should verify if these stones are natural and untreated, or if they have undergone any artificial treatments. Jewelers have the responsibility to disclose this information to you and it is important to avoid paying the price of a natural diamond for a treated stone.

Diamond treatments are usually used for improving the overall quality of the diamond, eliminating the inclusions or blemishes and adding or changing the color of the stones. Some treatments will be permanent and stable, while some others may suffer damage over time. Through this article, we list some of the commonly used diamond treatments:

Clarity Treatments

These treatments are specifically designed for improving the clarity of diamonds. A few of such treatments that are widely accepted in this industry are listed below:

Fracture Filling

This method is used to fill the cracks or fractures that are present on the surface of a diamond. It makes use of a glass-like material that has optical properties similar to that of diamonds. This treatment can improve the appearance of a diamond by approximately two clarity scales. However, fracture filling is not a permanent treatment.

A diamond that has undergone fracture filling can be easily identified by the flashes of changing color which can be seen under proper lighting. Other evidence includes a ‘crackled appearance’ of the filler material or the presence of bubbles inside the diamond.

Labs that grade diamonds will not provide a clarity or color grade to diamonds that are fracture-filled.

Laser Drilling

Laser drilling is a technique that is used to reduce the visibility of inclusions present in the stones. A microscopic hole will be drilled through the diamond in order to reach the inclusions with the help of a laser beam. Carbon dioxide lasers are used for this purpose, where a tiny area of a diamond will be heated until it evaporates, thereby forming a tube or tunnel that reaches the inclusions. After this, the inclusions will be washed away using certain acids.

By this treatment, the inclusions will become less visible and hence, the diamond will become more saleable. Laser drilling is used mostly in smaller stones and is a permanent diamond treatment method.

Laser drilling can be identified with the help of 10x magnification of the microscope. Some laser-drilled diamonds will be fracture-filled and they will show color flashes. Diamonds that are undergone both laser drilling and fracture filling will not be given a color and clarity grading.

Internal Laser Treatment

This treatment is also known by the name KM treatment. KM stands for the Hebrew term ‘KiduahMeyuhad’ which means ‘special drill’. In this treatment, there will be no drill hole or tunnel present, however, the laser may leave a worm-like squiggle inside the diamond.

Internal laser treatment is usually used to eliminate black inclusions that come along with internal fractures. This method creates an internal fracture on the stone by focusing one or more pulses of the laser beam on the inclusions. Then the inclusions will be bleached by the process of boiling the diamond in strong acid under high pressure. The feather resulted from this treatment is similar to natural feather, hence it difficult to differentiate. But it can be spotted by the high magnification of the microscope with the help of different lighting techniques.

Color Treatments

These treatments are used to add or change the color of diamonds. Commonly used color treatments include:

Surface Coating

It is used to apply a thin layer of colored foreign substances on the surface of a diamond. This treatment will either help to mask the original color of the stone or will accentuate the desirable color. The coating will be usually applied to the girdle and/or pavilion of the diamond.

The durability of the coatings used will vary based on the material and also the methods used for coating. More advanced techniques involve adding a really thin chemical or optical film that is more durable than the older methods. If this coating is damaged it can be picked by an experienced gemologist with the help of a microscope.

High Pressure High Temperature Treatment (HPHT)

This treatment is usually applied to all diamonds that have a slight brown color because of the distortion of the crystal lattice. When such diamonds are exposed to high temperature and high pressure, the irregularities in the crystal lattice will be removed, thereby eliminating the color.