Reports for Coloured Diamonds

Following the determination of the nature of a coloured diamond (synthetic or natural), the colour authenticity is tested. Treatments, such as HPHT treatment, can be applied to some fancy coloured diamonds in order improve their colour. These treatments consist either in coating the surface with a coloured substance, or in irradiating the whole or part of a diamond. This last treatment is the most common and is generally followed by a heat treatment (annealing). We disclose all these treatments according to CIBJO rules and our own internal standards. 
Diamonds with a of artificial colouration (e.g. high-pressure high-temperature treated diamonds) are disclosed as Treated Diamonds.

Colour authenticity:

In order to determine whether a diamond is of natural or artificial colour, the following investigations are routinely performed on loose stones:

  • Thorough observation with a binocular microscope in dark field, transmitted light, polarized light, and immersion (if necessary)
  • Quick test with a spectroscope
  • FTIR spectroscopy to determine the type of diamond (type IaA, IaA/B, IaB, Ib, IIa, IIb), the presence or absence of C-H stretching bonds and the presence or absence of irradiation/annealing absorption peaks (H1b, H1c) and other infrared characteristics.
  • UV-visible-near-infrared spectroscopy of the diamond, cooled down to approximately -120°C.
  • Photoluminescence spectroscopy of the diamond, cooled down to approximately -120°C.

Fancy colour diamond grades:

SSEF uses the widely accepted trade terms to disclose fancy colour diamond grades if their colour is natural:

  • faint
  • very light
  • light
  • fancy light
  • fancy
  • fancy intense

Content of natural coloured diamond report:

Reports for natural coloured diamonds are issued on gemstone reports stating:

  • Weight
  • Shape and Cut
  • Measurements
  • Colour
  • Identification
  • Comments concerning the colour authenticity of the diamond
  • Colour photo of the diamond