Gemstone Enhancement Codes
Gemstone
Enhancement
Code		 Meaning
N Not currently known to be enhanced, or known by Coast-to-Coast to be untreated
E Routinely enhanced by traditional methods.
B Bleaching:The use of heat, light and/or other agents to lighten or remove a gemstone's color
C Coating: The use of such surface enhancements as lacquering, enameling, inking, foiling or sputtering of films to improve appearance, provide color or add other special effects.
D Dyeing: The introduction of a coloring matter into a gemstone to give it new color, intensify present color or improve color uniformity.
F Filling: The filling of surface breaking cavities or fissures with colorless glass, plastic, solidified borax or similar substances, which are visible under properly illuminated 10x magnification. This process will improve durability, appearance and/or add weight.
H Heating: The use of heat to affect desired alteration of color, clarity and/or phenomena.
HP Heating and Pressure: The use of heat and pressure combined to affect desired alteration of color and/or clarity.
I Impregnation: The impregnation of a porous gemstone with a colorless agent (usually plastic) to give it durability and improve appearance.
L Lasering: The use of a laser and chemicals to reach and alter inclusions in diamonds.
O Oiling/Resin Infusion: The filling of surface breaking fissures with colorless oil, wax, resin or other colorless substances, except glass or plastic, to improve the gemstone's appearance.
R Irradiation: The use of neutrons, gamma and/or electron bombardment to alter a gemstone's color. The irradiation may be followed by a heating process.
U Diffusion: The use of chemicals in conjunction with high temperatures to product color and/or asterism-producing inclusions.
W Waxing/Oiling: The impregnation of a colorless wax, paraffin and oil in porous opaque or translucent gemstones to improve appearance.
SYN Synthetic materials which have essentially the same optical, physical and chemical properties as a naturally occurring counterpart.
IMIT Manufactured materials such as glass, plastic, or ceramic designed to imitate or resemble the appearance but not duplicate the characteristic properties of a natural gemstone.
ASBL Products made of multiple layers including combinations of manufactured and/or natural materials fused, bonded or otherwise joined together to increase stability and/or to imitate the appearance of a natural gemstone, create a unique design or generate unusual color combinations.