Diamonds and gemstones have for a long time been subjected to various treatments to enhance its appearance. Although the treatment methods are not new there are some that are newly developed and nearly impossible to detect without special equipment. The consumer may want to understand these treatments and the subsequent special care needed for some of these.

Most treatment methods are to improve the look of the gemstone. In the case of diamonds is to make it look whiter, more colored, or appear to have a higher clarity grade than it is. In gemstones it is usually to improve color, change color, and improve the clarity characteristics.

These are some of the commonly used treatment methods.

Oiling
Oiling a gemstone commonly done to emeralds is to bring out the rich green color. Colored oils help to enhance the color in certain gemstones such as alexandrites and rubies. Along with oiling, wax and other natural and synthetic resins are used to fill fractures improving its clarity appearance. Oiling is not permanent and special care must be taken in cleaning and repairing. Do not use detergents or solvents for they will remove the oils.

Heating
Heating the gemstone improves the color, either darkening, or lightening. It can also improve the clarity and brightness. It is the most common form of treatment for rubies and sapphires. Heat treatment is also used on aquamarines, tourmalines, topaz, citrine, tanzanite, amethyst, and zircon. Heat treatment is permanent and an acceptable form of enhancement. It does improve the look of the gemstone and may also increase its value. It most definitely would increase its salability. Beryllium heating produces yellow and orange color in sapphires.

Untreated sapphires and rubies are more valuable and would need a confirmation report from one of the recognized laboratories, AGS, GIA, AGL, etc.

Diffusion
Diffusion is most commonly used on corundums. It is a surface treatment that layers titanium and iron onto the surface of the gemstone. It is a thin coating that can be removed by polishing or scratching. It is not permanent.

Irradiation
Irradiation is a process of bombarding a gemstone with high energy rays to change its color. For most gemstones subjected to this procedure it is usually followed by heating. Irradiation will create colors not usually found in natural topaz. When diamonds are irradiated it is done using one of four different high energy methods. The type if irradiation will determine a particular result in depth or intensity. Diamonds are also annealed after irradiation to further enhance its color. The resultant colors are yellow, brown, pink, red, blues and greens and is permanent. Irradiated diamonds are difficult to detect without special equipment and confirmation should be done by a recognized laboratory.

Filling
Fractures in a gemstone can be filled with a resin or glass-like substance to improve its clarity appearance. In diamond, it is identified by color flashing. It is not permanent and is affected by heat and ultrasonic acid cleaners. Disclosure is necessary upon point of sale and the jeweler that has to do any work on it has to be informed of its condition before any repair work is done to the jewelry piece. Filling improves the salability of the diamond or gemstone but does not increase its value.

Dyeing
Dyeing is used to improve the color of gemstones commonly used on gemstones like jade. It may be difficult to detect and can make an inexpensive piece look more valuable. This also if it is an expensive piece its state should be stated on a report by the laboratories.

Lasering
Lasering is primarily used to change a dark inclusion in a diamond to a lighter one that is less visible. In the process a laser is used to drill a hole from the surface of the diamond to the inclusion after which an acid treatment will lighten the imperfection. Laser drill holes can be seen but may difficult to see depending on the position and angle of the hole. Newer laser techniques can disguise the laser hole to look a little more like a part of the natural flaw. Disclosure is an ethical necessity even though it is not a legal requirement.

HPHT
High pressure, high temperature treatment of a certain class of brown diamonds results in a much whiter diamond than it was previously. The process is difficult to detect without specialized equipment and laboratory confirmation is necessary. Most HPTP diamonds that are analyzed are identified with laser inscriptions. GE’s HPTP diamonds are identified with GE POL inscribed in the girdle. The process is not reversible.

Coating
Gemstones are occasionally coated with a colored film to improve its color. It is not permanent and will wear off. Coating a Cubic Zirconia with thin layer of diamond is not meant to enhance or add to its durability it as much as it is to deceive the buyer. It will fool standard diamond testers. People have known to have overpaid by thousands of dollars thinking that they were buying a diamond. Buying a diamond with certificate from AGS, GIA, EGL, IGI and other known laboratories will identify it as a diamond and will help to prevent this problem.

Enhancement techniques and processes do have its place in jewelry. It can make an inexpensive gemstone appear nicer without a huge cost. Disclosure is important since value can vary hugely different between treated and untreated gemstones. Caution is advised with any purchase.

Mahalo,
Russell Oshita
The Diamond Specialists Inc.

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