Gemstone Enhancements

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:


1) N: Those natural stones which are not currently known to be enhanced by any methods, such as spinel, and therefore can safely be presumed untreated. The symbol "N" is used for these and may also be used in the case of other stones which are sometimes or often treated, which in the particular case are unenhanced. To use this symbol on sapphire, for example, which is generally heated means that the seller certifies that the particular stone was not heated and supplies a document such as an invoice or lab report so stating.


2) E: Those natural stones which are routinely enhanced by traditional methods, the particular stone given this designation, may or may not be enhanced. For example, since most emeralds are oiled an E would indicate such treatment, but would not cover non-traditional methods such as hardened plastic resins (like Opticon) which would require specific enhancement codes such as those listed below. Another example would be the use of E for aquamarine, which in most cases is heated prior to the sale of the rough to remove greenish tints. If the seller knows what specific treatment has been used, then a more specific code should be used.


3) Those gemstones for which definite information on standard treatments is known, or to which N and E codes do not apply, as they have been treated in non-traditional ways which must be specifically disclosed by the appropriate code and also in writing. For example, a ruby which has had fractures or cavities filled with glass would receive an I (infilling) code as described below. A Morganite, which is known to have been heated, would receive an H rather than the less specific, E.



Specific Enhancement Codes:

B: Bleaching - Use of chemicals to lighten or remove a gem's color

C: Coating - Use of surface treatments such as films, lacquers, etc. to provide color or other special effects

D: Dyeing - The introduction of coloring matter into a gem to give it a new color or greater intensity

F: Filling - Incorporation of colorless borax or other substances into cracks as a by-product of heating the stone, used only if such material is visible at 10x.

G: Gamma/Electron Radiation - The use of gamma or electron irradiation for the purpose of changing a gem's color, may be followed by a heating process to stabilize the color. Such stones do not exhibit residual radioactivity.

H: Heating - The use of heat to clarify, change color or create phenomena in gems. Any filler materials, which enter the gem, as a result must not be visible in fractures at 10x.

I: Infilling - The intentional filling of surface breaking cracks and cavities with a foreign material such as synthetic resins with hardeners (Opticon), glass or plastic.

L: Lasering - The use of a laser to drill into a stone and remove or alter an inclusion, refers specifically to diamonds

O: Oiling or Resin Infusion - The intentional filling of surface breaking cavities and cracks in transparent or translucent gems with a colorless oil, wax, resin or man-made unhardened resin.

R: Irradiation - The use of neutron bombardment to alter color. This process creates residual radioactivity and such stones must receive a Nuclear Regulatory Commission safety release prior to sale. Usually used in combination with other radiation and or heating treatments.

S: Bonding - The intentional use of a colorless bonding agent (usually plastic) within a porous gemstone.

D: Diffusion - The use of specific chemicals during a high temperature heating process for the purpose of penetrating the surface layer (usually to a slight depth only) with coloring or star-making chemicals. Such treatment is not generally accepted and stones sold with this enhancement must be specifically labeled as diffused.

W: Waxing/Oiling - The impregnation of colorless wax, oil or paraffin into porous opaque gems to improve appearance.