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9 Most Common Gemstone Treatments

Have you ever been shopping for gemstone jewelry and heard your jeweler refer to various types of “gemstone treatments”? This term is used to describe the techniques to make them look better, brighter, or more colorful. While you may be inclined to believe that treating gemstones is shady business, there are several treatments that are widely used and accepted by the jewelry industry. Gemstone treatments serve to enhance a gemstone’s appearance without negatively affecting its value. On the other hand, there are some treatments that are widely discouraged, which we’ll explain in more detail.

Gemstone treatments are not typically visible to the inexperienced eye, which is why sellers are legally obligated to disclose any treatments used on a gemstone before it is purchased. A trusted jeweler, like Leo Hamel Fine Jewelers, will always be transparent with their customers about any treatments that were used on any gemstone for sale. If you’ve ever wondered about gemstone treatments and how they work, you’ve come to the right place. We’re listing some of the most used gemstone treatments, determining which work best, and which are most easily detected with the amateur eye.

1. Bleaching Treatment

Bleach is a chemical used to alter the color of a porous gem, such as jadeite or pearl. This treatment helps to lighten a gemstone’s color and remove unwanted discoloration. Bleach treatments are quite common, and nearly impossible to detect as a singular process. However, there are generally two steps to bleach-treating gemstones. The second step, known as polymer impregnation, can be detected by an expert using advanced analysis conducted in a specialized laboratory. While there are no price differences between bleached and unbleached gems, the acidic compound found in bleach can damage the structure of the gemstone and leave it more vulnerable to breaking. Additionally, bleaching a gem can increase its porosity, making it more susceptible to absorbing bodily oils and liquids.

Two gemstone pendants

2. Irradiation Treatment

Many gemstones are subjected to different forms of artificial radiation in order to alter their color. This process is often followed up with heat treatments to help further enhance the color. Irradiating gemstones involves bombarding them with particles such as electrons or neutrons on a subatomic level. A shopper might be worried about whether this process could affect their health, but the effects of the radiation are short and there are strict regulations that require these treated gems to be thoroughly tested and held until they are perfectly safe.

One common gemstone that is frequently exposed to irradiation treatment is blue topaz. In fact, almost every blue topaz on the market has been subjected to irradiation. This process creates vivid shades of blue that are not achievable in an untreated topaz. Depending on how long the topaz is subjected to radiation, its resulting color can range from Swiss Blue to London Blue. London Blue is the least common type because it requires the expensive process of neutron exposure.

Irradiation treatment is nearly impossible to detect in most gems. However, you may be able to identify an irradiated gemstone by examining the intensity of its color. For example, deep blue topaz simply doesn’t occur in nature. Therefore, if you espy a topaz gemstone with an unusually vibrant blue color, you can assume it has undergone some form of irradiation.

3. Dyeing Treatment

Dyeing treatments involve introducing a colored substance into gemstone that has surface-reaching fractures or a porous structure, in order to modify their color. Gems like agate, onyx, pearl, and coral are often subjected to this treatment to ensure an even coloring. In fact, dyeing agate dates back to ancient Roman civilizations.

In many cases, dyeing can be detected under a magnifying glass using a diffused light source. Experts can identify concentrated color on the surface and inside the fractures of a stone. However, there are certain gemstones like jade or turquoise where dyeing might not be as apparent. Dyeing treatments are common within the industry, especially for colored pearls.

Dyed gems tend to be more susceptible to fading, so it’s best to avoid direct sunlight. Additionally, solvents like acetone and rubbing alcohol can dissolve the gemstone’s dye, further dulling its color.

Various sizes & colors of gemstones

4. Heat Treatment

Undoubtedly the oldest practice in the book, heat treatment has been used for thousands of years to enhance the color and clarity of gemstones. Over the centuries, heat treatment has evolved, and now involves high tech computer-controlled furnaces.

Heat treatment is a completely legitimate practice. In fact, it is a natural continuation of the process that took place inside the earth’s crust when the gemstones were formed. Without heat treatments, we wouldn’t have nearly as many colored gemstones to enjoy.

The process involves heating the stone to high temperatures, which triggers chemical reactions that change the color of the stone. The two most important factors in this process are the temperature and the environment. Heating the gemstone provokes various chemical exchanges between the stone and the atmosphere on a molecular level. This helps to achieve one of the two most desired effects of heat treatment: changing a gemstone’s clarity or changing its color. For example, heat treatment is used to remove green undertones in an aquamarine or to produce deeper shades of blue in a topaz.

While heat treatment might not be obvious to you, an expert can often determine whether a gemstone has been subjected to heat by analyzing inclusions through a microscope, such as tiny crystals that melt when a gemstone is exposed to extreme temperatures.

5. Coating Treatment

Coating is a process used to enhance the appearance of the gem’s surface by adding a coloring agent to the entire gem, or just the back of a flat stone, referred to as backing. Gemstone coating is commonplace and can be easily identified by an expert unless the film is colorless. Quartz and topaz are two of the most frequently coated gemstones, evident from their unnaturally bold color and iridescence.

Thin film coatings are susceptible to scratching, as they tend to be much softer than a gem’s natural surface. Be sure to avoid contact with abrasive objects, and store your treated gemstone in a soft, dry cloth when you’re not wearing it.

Various sizes & colors of gemstones

6. Laser Treatment

Laser treatment is used to drill small holes into a gemstone to reduce the appearance of an inclusion, or dark spot within. An inclusion can be further vaporized or bleached if the laser does not burn through it completely. This treatment is reserved exclusively for diamonds, as they are the only gemstone strong enough to withstand the high heat from the laser. This treatment is very easily detectable due to the microscopic laser holes that can be spotted under magnification. Laser treatments are widely accepted, and do not affect the durability of a diamond. In addition, diamonds that have been treated in this manner require no special care.

7. Fracture Filling

Gemstones with surface fractures are subjected to fracture filling. This treatment involved using wax, glass, or borax to fill in these tiny cavities. Not only does this smooth out the surface, but it can also improve the gemstone’s clarity, stability, and overall appearance. Such treatments can easily be identified by a trained gemologist using proper magnification.

The practice of fracture filling is a recent one, though it is used on several popular gemstones like rubies, emeralds, and diamonds. So far, this technique has yielded great results, making gemstones more durable and extending their longevity. Depending on what was used as filler, some treated gemstones may require extra care. Drastic fluctuations in temperature and air pressure can remove the filler substance, so practice caution.

8. Diffusion

The process of diffusion involves heating a gemstone to very high temperatures while adding chemicals like beryllium. This strategy serves to enhance or change a gemstone’s color. Diffusion treatments are common in gemstones like ruby, blue sapphire, or green topaz. The original gemstone material is often much paler when compared to the final product, and the results are permanent.

Diffusion can be difficult to detect, though it can be confirmed in some cases using tools like a spectrometer. If you are thinking of purchasing a gemstone that has been subjected to diffusion treatment, bear in mind that the color may only be surface deep. Damage such as scratching or chipping could ruin the appearance of the stone by exposing its untreated surface.

Bracelet with various colors & sizes of gemstones

9. Oiling

Oil treatments are used to smooth visible fissures and cracks in a gemstone with filler like epoxy or polymer. This technique has been practiced for centuries, especially on emeralds which are known to have many internal fractures. The result is a drastic improvement of the gemstone’s brilliance and transparency.

Oiling is accepted within the industry, and while the treatment may be effective, it is not permanent. After some time, gemstones will need to undergo additional oiling treatments to keep them at their best. Gemstones are most usually treated with cedar oil, a natural product of the cedar tree. It’s a colorless, viscous substance that is used to fill the fractures because it has a similar refractive index to the gemstone. The oil is applied along with heat and pressure to properly fill in fissures. Depending on how many fractures were filled, the temporary effect of the treatment can be significant, moderate, or minor.

Colored Oils

While the oiling treatment described above is considered a standard procedure, there is another very similar technique that is high discouraged. It involved gemstones like emeralds and rubies being treated with colored oils that are meant to conceal their true color and the severity of their fracture. This is not a widely accepted practice, as it seeks to mask the true state of the gemstone. Fortunately, if you are buying jewelry from reputable sellers, you have nothing to worry about, as they won’t attempt to sell gemstones that have been treated in this way.

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