Coating

The painting and coating of gemstones is a practice that dates as far back as Roman and Greek times. It was considered at that time as a normal way to enhance the appearance of a gemstone. A paint like colouring agent was applied to the back surface of the gem material (backing) or as a coating to part or all of the gemstone surface in order to alter the colour appearance of the gem material. More modern techniques involve applying a thin layer of Titanium or Cobalt to the surface of the gemstone which can affect both colour and brilliancy. When such a treatment is detected at the surface of a gemstone, it will be disclosed under the Identification section of the Report as Coated, with additional details of the treatment addressed in a footnote.

Irradiation

Some gemstones may be artificially irradiated to change their colour appearance. The process involves neutron or electron bombardment, or the use the radioactive isotope Cobalt 60 that will affect the atomic structure of the gemstone’s crystal lattice and dramatically alter the colour of the stone. Topaz, Tourmaline, Beryl, diamond and others are routinely treated in such a manner. The irradiation may also be accompanied by a subsequent heat treatment and is, in most cases very challenging to detect from a gemological point of view. Please note that fade tests are normally not conducted by the Laboratory. When such a treatment is detected in a gemstone, it will be disclosed under the Identification section of the Report as Irradiated, with additional details of the treatment addressed in a footnote.