Following is the list of the abbreviations we use for "Enhancement" that appear in the details section for each Gemstone we offer:

A (None)	Indicates either a gemstone that is not currently known to be enhanced or one that is so rarely enhanced that to give it an "E" symbol would mislead the public. Example: Amethyst is rarely known to be treated.
B	Indicates that Bleaching of the gemstone has been done. Bleaching is the use of chemicals or other agents to lighten or remove a gemstone's color. Example: 'Blonde Tigereye" is enhanced in this manner.
C	Indicates that a Coating has been used as a surface treatments such as waxing, lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, provide color or add special effects.
Cedar Oil	Cedar Oil treatment used for emeralds to fill the natural cracks and fissures within the stone improving how light may pass through the stone.
D	Indicates that Dyeing has occured. Dyeing is the introduction of coloring matter into a gemstone to give it new color, intensify present color or improve color uniformity. Example: Agate is sometimes enhanced in this manner.
F	Indicates the gemstone has had Filling or Infilling or Stabilizing of some form. This is the filling of surface-breaking cavities or porous gem material with colored or colorless glass, plastic or other hardened material to improve appearance, durability, and/or weight. Example: Turquoise is commonly enhanced in this manner.
H	Indicates the stone has been heated to effect desired alteration of color, clarity, and/or phenomena. Example: Sapphire is commonly enhanced in this manner. Example: Citrine is commonly enhanced in this manner.
Mix
N	Indicates this particular gemstone has received no enhancement and the seller will guarantee this.
R	Indicates the gemstone has undergone Irradiation. This is the use of neutron or a combination of neutron with any other bombardment to alter a gemstone's color. May be followed by a heating process ("H"). Example: Blue Topaz is commonly enhanced in this manner.
T	The treatment is a heat diffusion process in which an ion foreign to the original chemical composition of the sapphire is deliberately diffused into the sapphire. The color completely penetrates the stone. This treatment is permanent.

Also see Gemstones Clarity Grades Explained .