The following chart explains the enhancements and treatment codes that you will see on our website. They are derived from industry standard codes which we have amended for further clarification.


  • N = Natural (No enhancement)

Gems that are, according to best available information, untreated.

  • H = Heat only

Enhancement via heat only.

  • U = Diffusion

Enhancement by the diffusion of foreign elements into the crystal lattice of a gemstone. Example: Beryllium-diffusion.

  • HP = Heat & Pressure

Enhancement via extreme heat and pressure. Also referred to in the industry as HPHT (High Pressure High Temperature)


  • F = Filling

Enhancement by filling a gemstone's cracks and crevices with a colourless substance. Fillers include, but are not limited to, glass, plastic, resin, wax, and oil.


  • FD - Filling & Dye

Enhancement by filling cracks and crevices with a coloured substance. Fillers include but are not limited to, glass, plastic, and resin.


  • D = Dyeing

Enhancement by the introduction of a colouring agent into a porous gemstone.


  • IR = Irradiation

Enhancement of colour via the use of neutrons, gamma, ultraviolet, and/or electron bombardment.


  • TPL = Triplet

To add a clear protective layer on top of a Doublet. The top layer may consist of clear quartz, glass or hard plastic material. This is used to thicken and give additional strength to the item.


  • C = Coating

Enhancement by the application of an artificial layer to the surface.


  • B = Bleaching

Enhancement by heat, light, and/or chemical agents to lighten or remove colour.


  • O = Oiling

Enhancement by bathing the gemstone in an oil to enhance the lustre and clarity of a gemstone.


  • R = Reconstruction

Enhancement by use of heat, pressure, and/or solvents to fuse small pieces of a gem together into a larger whole. Often used in conjuction with a dye.


  • I = Impregnation

Enhancement by melted wax or plastic forming a layer over the surface of a gemstone to improve amongest other things lustre.


  • A = Assembled

Enhancement by assembling other substances over or under a gemstone to improve durability and size.


  • S = Smoking

Enhancement by smoking a gemstone and replacing its water content with carbon. Sometimes the smoke can be dyed.


  • DBL = Doublet

A thin layer of natural stone adhered to a backing material. The doublet backing material is used to thicken and give strength to the item.


  • HTLE = Heat and Light Elements

Enhancement by adding a chemical element during the heating process of a gemstone.

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