The ATGA Guide to Gemstone Treatment
ASBL - Assembled from multiple layers or combinations of manufactured and/or natural material fused, bonded or otherwise joined together to increase stability and/or imitate the appearance of a natural gemstone, create a unique design or generate unusual color combinations. Example: Opal triplets.
B - Bleached using heat, light and/or other agents to lighten or remove color.
C - Coating on the surface with such enhancements as lacquering, enameling, inking, foiling or sputtering of films to improve appearance, provide color or add other special effects.
D - Dyed by the introduction of coloring matter to give a new color, intensify present color or improve color uniformity.F - Filling of surface-breaking cavities or fissures with colorless glass, plastic, solidified borax or similar substances (visible under 10X magnification); improves durability, appearance and/or adds weight.
H - Heated to effect desired alterations of color, clarity and/or phenomena.
HF - Heated to effect desired alterations of color, clarity and/or phenomena and displays a residue of foreign substances in open fissures that is visible under properly illuminated 10X magnification.
HP - Heat and pressure is combined to effect desired alterations of color, clarity and/or phenomena.
IMIT - Imitation product fabricated in such materials as glass, ceramic or plastic designed to imitate or resemble the appearance, but not duplicate the characteristic properties of a natural gemstone.
I - Impregnated using a colorless bonding agent (such as plastic); used on porous gemstones to add durability and improve appearance (usually referred to as "S" stabilized).
L - A laser and chemicals used to reach and alter inclusions in gemstones, usually 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 using neutrons, gamma rays, beta particles or high energy electrons to alter color. May be followed by a heating process.
S - Stabilized using a colorless bonding agent (such as plastic); used on porous gemstones to add durability and improve appearance (sometimes referred to as "I" impregnated).
SYN - Synthetic materials with essentially the same optical, physical and chemical properties as a naturally occurring gemstone.
U - Diffusion; chemicals used in conjunction with high temperatures to produce color and/or asterism-producing inclusions.
W - Waxing/oiling; impregnation of colorless wax, paraffin and oil in porous, opaque or translucent gemstones to improve appearance.