Gem Treatment

Loose Gemstones:

Specials Product:
CODE: D001

Diamond Rough
0.3 - 1.5 carat
USD $ 190/Crt
Detail report
CODE: Z001

Emerald Rough
1.5 - 10 carat
USD $ 40/Crt
Detail report
CODE: R001

Ruby Rough
1.5 - 10 carat
USD $ 40/Crt
Detail report
CODE: S001

Sapphire Rough
1.5 - 10 carat
USD $ 40/Crt
Detail report
CODE: Y001

Yellow Sapphire Rough
1.5 - 10 carat
USD $ 40/Crt
Detail report
CODE:  C001

Cat Eyes Rough
1.5 - 10 carat
USD $ 30/Crt
Detail report

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Gem Treatment

Many gemstones are treated with various methods to improve color and clarity. Some of these methods are widely accepted in the trade today, while other methods are not. The accepted trade methods are the ones that will change the color of the gemstone permanently.
All ethical gem dealers will fully disclose gem treatments. But in our view it is also important to provide detailed information to the buyer so that he knows exactly what he is buying. So we have added information below that will help educate you about the common treatments, as well as some recent innovations. Keep in mind that most colored gemstones are treated, and this is a perfectly legitimate practice as long as all facts are disclosed to the buyer. If you know the facts, then you can feel safe about buying a gemstone that you will enjoy for many years to come.

1. Heat Treatment
Centuries ago, someone stumbled upon the magical effect of applying heat to gemstones. High heat, such as that from a charcoal fire, can make a bland looking gemstone change its color into something spectacular. If this fortunate technique were not discovered, there would be very few affordable gemstones of good color in the market.
Heat treatment is considered a natural type of enhancement as it is a continuation of the processes that occur in the earth when the stone was originally formed. During treatment, the stone is heated to very high temperatures (approximately 1600 Centigrade) causing inclusions, chemical elements, and other impurities to reform themselves and change the color of the stone. This color change may result either in the stone being darker, lighter, more intense, or of a different color. An example of this is the dissolving of rutile silk inclusions in blue sapphires, which improves both clarity and color. This heat treatment is permanent and irreversible.

2. Beryllium Treatment
Beryllium treatment is a recent addition to techniques for treating gemstones. Beryllium treatment is a form of heat treatment, mainly for sapphire, that adds the element beryllium to the heating process. Beryllium is an element well known in the gem world, since it is an essential constituent in many gemstones, including emerald, beryl, aquamarine and chrysoberyl. When sapphires are heated with beryllium, the result is a reduction in blue tones. Thus bright yellow or orange sapphire can be produced from weak yellow or greenish gems. Some stunning colors have been produced using this method.
This method is sometimes known as lattice diffusion. However, unlike some older forms of diffusion treatment, with beryllium diffusion the new color is deep within the stone; and these stones can be recut if needed. This is unlike the older diffusion treatment process, which only colors the surface of the stone. After some initial controversy, beryllium treatment is now widely accepted in the gem business as a legitimate method for treating stones. However, it is very important that gems treated with this method be disclosed as such. The most common terms are “Beryllium treated” or “Be treated” (”Be” is the symbol for the chemical element beryllium).

3. Diffusion Treatment
A treatment that one should be aware and cautious of is diffusion treatment. There is some controversy surrounding this method of treatment. Diffusion treatment consists of exposing the surface of the stone to certain chemicals combined with high heat in a furnace. Generally, only the surface color changes, so if you sliced the gem in half, the inside of the stone would be a different color, usually a paler, less valuable color. The problem is the new surface color is not very deep, only about half a millimeter. If the stone is damaged or perhaps recut, then the original, undesirable color will be noticeable. Beware of this treatment. As of now, the method is used to change the color of ruby, green topaz, and blue sapphire. Usually the original material is a pale or almost colorless stone that is treated to change the color of the surface. Until methods are perfected where the entire stone color is changed, reputable dealers will always tell you which stones have been altered by this method of treatment. Some dealers even refuse to trade in these stones.

However, for star sapphires, this practice is more accepted. GemSelect deals in star sapphires that are diffusion treated. Diffusion treatment is a popular method for treating star sapphire, as the treatment will increase the asterism (the star effect in sapphire and ruby). The diffusion process may reach half a millimeter of depth into the gemstone. The process creates the star effect on the gemstone and the stone can be sold as a diffused star sapphire. The hardness of the gemstone is not affected by the diffusion process and the gemstone therefore keeps its original physical properties. A sapphire made into a diffused star sapphire cannot be polished or recut for the second time as the treatment is only on the surface of the stone. Polishing or recutting would take off this surface treatment. However, most buyers never repolish or recut the gemstones set in jewelry. This is especially true of sapphires, as they are hard and scratch resistant gemstones.

4. Fracture filled treatment
Small cracks or fractures in a gemstone can interrupt the flow of light through the stone, creating white or “dead” spots in the color of the stone. Sometimes these fractures–if they reach the surface of the stone–will be filled with material that will allow the light to pass through smoothly. Different chemicals are used; oil, wax, glass, epoxy, and borax are common materials. These tiny filled cavities are difficult to see without the aid of optical instruments, so the buyer should be aware of this practice. The most commonly filled stones are emerald, aquamarine, ruby, sapphire, peridot, and turquoise. It is accepted for emeralds to be oiled, as they are naturally heavily fractured.
The process of fracture filling ruby with transparent lead glass is a recent innovation that began about 2004 in Chanthaburi, Thailand. Rubies of good color, primarily from Madagascar, that are disfigured by fissures or surface cracks can be “repaired” using heat treatment with lead glass. The refractive index of corundum and lead glass are very similar, allowing light to travel through the stone, improving the color and clarity. These rubies are often found in large sizes at a fraction of the cost of untreated ruby of similar color. So they represent an excellent value in the market, so long as the treatment is disclosed and the price is appropriate.

The Asian Institute of Gemology tested fractured filled rubies for durability and found them to be more durable than a typical emerald fracture-filled with oil or resin. AIGS advised against excessive heating with a jeweler’s torch, but found no negative effects from cleaning with detergents or ultrasonic devices. They advise that hydrofluoric acid should not be used on these gems, and that any recutting or repolishing should be performed with care.

5. Irradiation Treatment
Virtually every blue topaz sold in the market today is the product of irradiation treatment.
Blue topaz is actually very rare in nature, and tends to a very pale blue. The lovely blue topaz we find today are produced by subjecting clear topaz to large doses of electrons from a linear accelerator or by exposing them to neutrons from a nuclear reactor.
The color in topaz is produced from defects in the crystal structure rather than from chemical elements in the stone. So exposing topaz to radiation induces color changes by modifying the way in which the crystal structure absorbs frequencies of light.
Depending on the duration and type of irradiation, and the sort of heating process used afterward, the results vary from sky, to Swiss to London blue. Other slight color variations have been produced and given their own tradenames like “electric blue” and “neon blue”. London blue is the scarcest and most expensive type because it requires neutron exposure (the most expensive process), and the longest holding times.
Although the irradiation of gemstones can leave some residual radioactivity, its duration is relatively short. Government agencies in the USA, and other gem irradiating nations, have strict regulations for the holding and testing of irradiated gems to assure that they are not released to the public until they are safe to handle and wear.

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