Enhancement Codes

On all Memos and Invoices received from Mayer and Watt, each gemstone will be classified with an Enhancement code to delineate enhanced and un-enhanced material, and what process they have been subject to. We at Mayer and Watt, guarantee the integrity of any gemstone we sell. The Enhancement Codes that we use, are those recommended by the AGTA and are more detailed and extensive than those required by the FTC.

• N = Not Enhanced
• D = Dyeing
• HP = Heat & Pressure
• O = Oiling/​Resin Infusion
• SC = Special Care Required
• B = Bleaching
• F = Filling
• I = Impregnation
• R = Irradiation
• W = Waxing/​Oiling in Opaque Stones
• C = Coating
• H = Heating
• L = Lasering
• U = Diffusion

* Codes and types of treatments must only be used as directed in the Gemstone Information Manual (GIM), available online at https://​agta​.org/