spacer John Dyer, Gemstone Artist

Fancy Cut Citrine
Leaf Shaped Blue Green Tourmaline
Radial ray cut rhodolite
Cushion cut blue sapphire
Dreamscape cut lime citrine
Pink tourmaline oval cut
Dreamscape aquamarine
Fancy cut ametrine

AGTA Enhancement Codes

Definition: ENHANCEMENT = Any treatment process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.

The following table describes the AGTA enhancment codes we use on our site.
For other codes visit .

If you have any questions about treatments that a specific gem has undergone please contact us and we will gladly give you more information.

Code Name Description

No Treatment
The "N" symbol can be used for stones in the event that a stone has received no enhancement and the seller will provide a guarantee that there has been none.
FFillingAs a by-product of heat enhancement, the presence of solidified borax or similar colorless substances which are visible under properly illuminated 10X magnification.
HHeatingThe use of heat to effect desired alteration of color, clarity, and /or phenomena. (Residue of foreign substances in open fractures is not visible under properly illuminated 10X magnification.
IInfillingThe intentional filling of surface breaking cavities or fractures usually with glass, plastic, opticon with hardeners and/or other hardened foreign substances to improve durability, appearance and/or weight.
OOiling/Resin InfusionThe intentional filling of surface breaking cavities of a colorless oil, wax, natural resin, or unhardened man-made material into fissured transparent/translucent gemstones to improve appearance (i.e., oil, man-made resin, cedar wood oil, Canada balsam, paraffin, etc.).
RIrradiationThe use of irradiation to alter a gemstone's color, may be followed by a heating process.

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