Treatments for Colored Gemstones

In today’s technically advanced world, all of us should be aware of exactly what we are purchasing in the gemstone world. Treatments, synthetics, and imitations can easily look like the real thing! Consumers need to know about treatments because they can easily affect the price of the gemstone and would also determine how a jewelry piece would be repaired or re-sized. I am going to discuss the different treatments so you know about them, but at the same time keep the amount of science down to a minimum (for both of our sanities)!

A treatment in colored gemstones is defined as any human-controlled process beyond cutting and polishing, that improves the appearance, durability, or value of a gem grown by Mother Nature. A treated gemstone is not a synthetic or an imitation. Those are completely ‘grown’ by man in a lab, Mother Nature had nothing to do with it. There are those that say a synthetic could be defined as “real” because it has the same chemical structure as a real gemstone, but it all goes back to the fact that they were developed by man, therefore they are synthetics. So please be aware of this whenever you are shopping for colored gemstones and yes, thanks to new technology, now even diamonds.

Any reputable and ethical dealer should disclose this information to you willingly. However I would go under the assumption that the colored gemstone you are looking at is most likely treated in some form, which may or may not be known. I have heard (but could not verify) that the amount of treated colored gemstones in the marketplace today could be as high as 80% – 95%!  The Federal Trade Commission (FTC) provides the framework of industry ethics. If you are interested in reading the full description by the US FTC, you will find it in Section 23.22 entitled “Disclosure of Treatments to Gemstones”.

There are ten types of gemstone treatments:

1: Bleaching

A treatment that uses chemicals to lighten or remove color. Cultured pearls are commonly bleached to remove dark spots and produce a uniform color.

2: Cavity Filling

Treatment that fills and seals voids to improve appearance and add weight. This treatment is often found in rubies.

3: Colorless Impregnation

Filling of pores or other openings with melted wax, resin, polymer, or plastic to improve appearance, luster and stability. Commonly used in turquoise and jadeite. Dye could be added to the filler. This would be considered two treatments, impregnation and dyeing.

4: Dyeing

A treatment that adds color or affects color by deepening it, making it more-even, or changing it. Like bleaching, dyeing is done mostly to porous gems such as jadeite, coral, and cultured pearls.

5: Fracture (Fissure) Filling

Using a filler to conceal fractures and improve the apparent clarity of a gem. The fillers include plastic, glass, polymer resins, and oils (Canadian balsam, cedarwood, and palm oil). Emeralds almost always have fracture filling as well as rubies. Due to this type of treatment, whenever having a repair done to a piece of jewelry with an emerald or ruby, always insist on the jeweler using no heat. I would even go so far as to have “no heat” written on the repair ticket. Also if a jeweler offers to clean that piece of jewelry, again insist on no heat. Most ultrasonic cleaners that jewelers use are heated.

6: Heat Treatment

Heat treatment is one of the oldest and most common of treatments. Heat treated gems were found in the tombs of ancient Egyptian kings. Heat treatment is exposing a gem to rising temperatures for the purpose of changing it’s appearance, usually color.

7: Irradiation

Exposing a gem to radiation to change or improve the color of the gem, however it is possible for the new color to revert back to the original color. Sapphires and tourmalines are likely candidates for irradiation.

8: Lattice Diffusion

The penetration of certain elements into the atomic lattice of a gemstone during heat treatment, with the objective of changing or accentuating its color.

9: Sugar and Smoke Treatments

Used on opals to bring out the play-of-color (the multiple colors usually found inside opals), sugar treatment is soaking an opal in a hot sugar solution and then sulfuric acid to deepen the color of the opal. Smoke treatment is heating a wrapped opal until smoke or ash penetrates the surface to darken the color of the opal. Of these two processes, sugar treatment is the most common. (FYI, it is a good idea to soak your opals in distilled water every once-in-a-while so they do not lose their moisture which then leads to damage.)

10: Surface Modification

Altering a gem’s appearance by applying backings, coatings, or coloring agents. The three basic methods are backing, coating, and painting. Backings to gems include silver or gold foils, fabric, paper and even colored feathers. Backings have fallen from fashion and are not commonly seen in gemstones, but are often used in costume jewelry. One gemstone that we do commonly see today that has a backing is mystic topaz. Since heat can often melt the backing, mystic topaz should not be exposed to heat. Coatings include wax, varnish, plastic, ink, and metallic compounds. Painting gem materials is another ancient practice from the Renaissance period (1300’s – 1500’s). Painting was obviously done with paint, but also ink, and nail polish.

As I am sure you have noticed, treatments are used to improve the color, clarity, and durability of a gem. Treatments are not a bad thing. Because of treatments, lesser gems can be treated to become beautiful gems and at a more affordable price, making them available to more people. If it were not for treatments, the industry would be limited to the supply of naturally created gemstones beautiful and durable enough to use as gems. In that case, the mighty and the rich would be the only ones to own them.

Gem Lady Treasures proudly uses natural gemstones, but that is not to say that at times we would use a treated gem. For example, in my quest for locating turquoise, I am looking for a turquoise that has been treated for stabilization (but not color) because it is a notoriously unstable gemstone. Of course, we would disclose the treatment.

I hope that you found this article helpful, interesting, and maybe even eye-opening. If you are interested in even more detailed information on treatments, Click Here to access “An Introduction to Gem Treatments” from GIA. Gemological Institute of America (GIA) is a world renown institute known for its research, education, and ethics in the field of gemology.

*Information for this article was provided by “Colored Stone Essentials” by GIA (11/2008).

Author: gemladytreasures

Please let me introduce myself, my name is Karen M. Smith and here is a little bit about me.

I have always been a lover of dogs. As a matter of fact, my dogs are known as my Fur Babies. I was in the fine jewelry industry where I fostered my love of colored gemstones. I cannot even begin to tell you how excited I am to now be able to combine my two favorite loves!

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