(AGTA) AMERICAN GEM TRADE ASSOCIATION ENHANCEMENT CODES
ENHANCEMENT: Any traditional process other than cutting and polishing that improves the color, clarity or durability of a gemstone.
N – NATURAL: stones which are not currently known to be enhanced.
ASBL – ASSEMBLED: stones made with a combinations of layers of natural and/or manufactured stones bonded together to increase the stability of the stone or imitate the appearance of a natural stone.
B – BLEACHING: the use of chemicals to lighten or remove a gems color.
C – COATING: the use of surface enhancements such as lacquering, enameling, inking or foiling to improve the appearance, provide color or add other special effects.
D – DYEING: the introduction of coloring agents into a gemstone to give it a new color or improve color uniformity.
F – FILLING: the filling of surface breaking cavities with colorless glass, plastic, solidified borax or similar substances. This will improve the appearance and add weight to the stone.
H – HEATING: the use of heat to effect the alteration of color and clarity within a gemstone.
IMIT – IMITATION: defined as man made stones used to simulate the appearance, but not duplicate the actual properties of the gemstone it is imitating.
O – OILING/RESIGN INFUSION: the filling of surface breaking fissures with colorless oil, wax or other colorless substances to improve the gemstone’s appearance.
SYN – SYNTHETIC: used to describe ‘synthetic’ stones that have essentially the same optical, physical and chemical properties as it’s natural counterpart.
R – IRRADIATION: the use of neutrons, gamma rays or high energy electrons to altar a gemstones color. The irradiation may be followed by a heating process.
U – DIFFUSION: the use of chemicals in conjunction with high temperatures to produce artifical color.