Treatment and Enhancement Guide
The process of enhancing a gemstone to bring out its beauty is a generally accepted practice and is defined as any treatment other than cutting or polishing that improves its appearance, durability or availability. These gemstones are formed deep within the earth's surface during which they undergo natural treatments of heat and pressure. These naturally occurring gemstones are rare and are inordinately expensive and can be afforded by only richest of people in the pure form. So in order to make them available to the public many companies treat them with heat, pressure and other techniques. Some enhancements improve on nature, cannot be detected and are permanent; this provides the gem market with a larger supply of beautiful gemstones. Other treatments produce dramatic changes in the gemstone itself or its clarity. A few treatments are less stable and should be avoided by the knowledgeable buyer. It has been approximated that 80% of the gemstones have been treated in some or the other way.
The following codes and definitions are adapted from the American Gem Trade Association's Gemstone Enhancement Manual, Edition 6.1 June, 1997, which is the industry standard for disclosure to consumers.
General Enhancement Categories
The gemstones can be divided into 3 major categories:
1) N: This symbol is used to represent all the naturally occurring gemstones that have not undergone any treatment or enhancement. For e.g. Spinel can be safely considered as untreated or un-enhanced. This symbol can also be used to denote those stones which are treated either sometimes or often.
2) E: Those natural stones which are routinely enhanced by traditional methods may or may not be considered to be enhanced as most enhancements are difficult or impossible to prove. For e.g. emeralds are generally oiled, so such a treatment will be indicated by an 'E' and would not cover non-traditional methods which would require specific enhancement codes such as those listed below.
3) There are certain gemstones for which either definite information about standard treatments is available or to which N and E codes do not apply due to non-traditional treatments. The specific treatment that these types of stones undergo must be disclosed with the appropriate code. For example, a morganite is known to have been heated, so it would have the code H rather than the less specific E.
Specific Enhancement Codes
Here are some codes that are generally used to represent the gemstones that undergo specific enhancement.
B: Bleaching - Organic gems like pearl, coral and ivory are treated with chemicals for the purpose of lightening the color. The effect of bleaching is permanent and undetectable.
C: Coating - To improve the appearance and to provide color and other special effects, the gemstones are enhanced on surface with lacquers, enamels, foils and films etc. Coating is generally a temporary treatment. The coats tend to worn or chip off so it is advised not to use harsh solvents or chemicals on such stones.
CR: Created/Synthetic Stone - These are man-made gemstones that have been generated in the laboratory and essentially have the same optical, physical and chemical properties as a natural occurring counterpart. Example - Mossanite
D: Dyeing - The improvement in the color intensity and color uniformity of the gemstones can be achieved through the introduction of a coloring matter. A gemstone can also be given an entire new color through dyeing. Chalcedony is dyed to form Black Onyx
F: Filling - This is done on gems that have fractures or cavities. Colorless borax, glass or plastic is incorporated into the fractures. The filler material must be visible under illuminated 10X magnification. Example - Opal
G: Gamma/Electron Radiation - This involves pounding gemstones with gamma or electron radiation followed by a heating process. The purpose is to change the color and stabilize it. Such stones do not exhibit residual radioactivity. Example - Blue Topaz
H: Heating - This is the most common treatment which lightens, darkens or completely changes the color of the gemstone. It can also be used for clarifying and creating phenomenon in gems. Any filler material entering the gem as a result of the process is not visible in fractures at 10X magnification. Ruby, Sapphire, Tanzanite, Aquamarine, Amethyst are most commonly heated stones.
I: Infilling - The cracks and cavities that generally appear on the surface of gems are intentionally filled with foreign materials like glass, plastic and synthetic resins with hardeners to improve upon the durability, appearance and weight. It is generally used on diamonds to increase clarity.
L: Lasering - It's generally used on diamonds and involves removal or alteration of an inclusion that detracts the beauty of the stone with the use of laser. Tiny holes are drilled into a diamond to access the inclusion which can then be vaporized or bleached.
O: Oiling or Resin Infusion - The transparent or translucent gems bearing surface breaking cracks and cavities are intentionally filled with colorless oil, wax, paraffin, cedar wood oil, Canada balsam, resin or man-made unhardened resin, etc. to improve the appearance. Emeralds are generally oiled.
R: Irradiation - The gemstones are bombarded with neutrons or subatomic particles for the purpose of altering the color. The stones enhanced by irradiation are subjected to a Nuclear Regulatory Commission (NRC) safety release before selling. This process is usually used in combination with other radiation and/or heating treatments. Tourmaline is irradiated to intensify its pink color.
S: Bonding - A colorless bonding agent (commonly plastic) is used intentionally within a porous gemstone in order to improve upon the appearance and durability. Example - Turquoise
TA: Type A Jade - This type of jade has not been treated in any way except surface waxing.
TB: Type B Jade - If a natural Jade is promising but stained then it is treated with chemical bleaches or acids and is then impregnated with wax or clear polymer resin. This process significantly improves the transparency and overall appearance of the stone.
TC: Type C Jade - Natural jade is artificially stained or dyed. The red color of Red jade can be enhanced with heat but the translucency is usually lost.
DS: Diffusion - In order to improve upon the hue and saturation the gems are heated to a very high temperature in the presence of materials with chromophores like titanium, chromium which diffuse into the stones surface to change color or create phenomenon. Such type of treatment is not accepted and stones being sold with this type of enhancement are required to be specifically labeled as diffused. Sapphires are sometimes diffused on surface.
W: Waxing/Oiling - Gemstones with a vulnerable porous surface or with microscopic surface imperfections are coated with paraffin, colorless oil or wax to boost up their polish luster. Lapis Lazuli is generally waxed.
DBL - Doublet- It uses a backing material which is adhered to a thin layer of natural stone. This is done to provide strength and thicken the item.
TPL - Triplet- On top of a doublet a clear protective layer is added in order to thicken and give additional strength to the item. This top layer may be of clear quartz, glass or hard plastic material.
BL: Bleaching
CO: Coating
CSS: Created/Synthetic Stone
DY: Dyeing
FL: Filling
GER: Gamma/Electron Radiation
HT: Heating
INFL: Infilling
LSR: Lasering
ORI: Oiling or Resin Infusion
IRR: Irradiation
BND: Bonding
TAJ: Type A Jade
TBJ: Type B Jade
TCJ: Type C Jade
DF: Diffusion
WO: Waxing/Oiling
DB - Doublet
TP - Triplet
