These symbols, set by the American Gem Trade Association (AGTA) to disclose any enhancements that may have been applied to our gemstones prior to sale. For the benefit of you and your customers, I encourage you to use these symbols when you buy, display and sell stones and stone-set jewelry. Honesty and full disclosure is always the best practice, and the best way to build customers for life.
ASBL: Assembled from multiple layers of manufactured and/or natural materials. Example: opal triplets.
B: Bleached using chemical agents to lighten or remove color.
C: Coated on the surface to improve appearance or to add color or other special effects.
D: Dyed to provide, intensify or improve color.
E: This indicates a gemstone that is routinely enhanced though the exact enhance-ments are difficult or impractical to verify.
F: Fissures filled with solidified borax or similar colorless substance (visible under 10X magnification); a result of heat enhancement.
G: Gamma/electron irradiated to alter color; may be followed by heating.
H: Heated to cause an alteration of color, clarity or other quality.
IMIT: Imitation product, fabricated to imitate the appearance, but not the characteristic properties, of a natural gemstone.
N: Natural stones, not known to be enhanced.
O: Intentionally filled surface cavities, usually with a colorless oil, wax, natural resin or unhardened man-made material; used in transparent or translucent gemstones to improve appearance.
R: Neutron irridiated (requires an environmental safety release from the NRC) that is combined with any other bombardment and/or heat treatment to alter a gem’s color.
S: Stabilized using a colorless bonding agent (such as plastic); used on porous gemstones to add durability and improve appearance.
SYN: Synthetic or man-made material which has essentially the same optical, physical and chemical properties as the naturally occurring gemstone.
U: Diffusion; chemicals used in conjunction with high temperatures to produce color and/or asterism (star-like) inclusions.
W: Impregnated with colorless wax, paraffin and/or oil; used on porous, opaque gemstones to improve appearance.