CIBJO Diamond Reports

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Colourless to near colourless loose diamonds are usually submitted to SSEF for a 4C (Carat, Colour, Clarity, Cut) quality grading. This quality determination follows the CIBJO rules, edited in the Diamond book which may be downloaded from their website, CIBJO. Stones under 0.20 ct are not graded. A simplified CIBJO diamond report is issued for stones between 0.20 and 0.46 ct. For stones over 0.46 ct, the following rules apply:

Carat:

All weights are reported in carats (1 ct = 0.2 grams) with a precision to the third digit after the decimal point.

Colour:

The colour grade of a diamond is defined by comparing it with a CIBJO masterstone set (C1) and with two additional SSEF masterstone sets for better accuracy.
The colour grades issued on diamond reports are:

  • exceptional white + (D)
  • exceptional white (E)
  • rare white + (F)
  • rare white (G)
  • white (H)
  • slightly tinted white
  • tinted white
  • tinted colour

Clarity:

The clarity grade is technically estimated according to the CIBJO rules:

  • Loupe-clean
  • VVS 1
  • VVS 2
  • VS 1
  • VS 2
  • SI 1
  • SI 2
  • Piqué I (PI)
  • PII
  • PIII

Cut and shape

are reported in accordance with the usual trade names.

Other items stated on CIBJO Diamond Reports are:

  • Measurements
  • Proportions
  • Symmetry and Polish
  • Properties of the girdle (thickness, polish, and finish)
  • UV-fluorescence
  • Comments:
    a) Internal graining is considered as an internal growth characteristic, thus is not taken into account to downgrade a diamond from loupe clean to a lower grade.
    b) Extra facets and naturals are the main external characteristics. If such characteristics are present in the stone, the are mentioned under comments.
    c) Laser drilled diamonds are graded, but the laser drilling is mentioned under comments.

All red marks plotted on the diagram characterise internal features. All green marks plotted on the diagram characterise external features (mainly extra facets and naturals).

According to CIBJO rules, diamonds with fissure treatments (Koss, Yehuda etc.) are not graded.

Diamonds with a reduced colour (high-pressure high-temperature treated diamonds) are disclosed as Treated Diamond.

For more information, please refer to our STANDARDS & APPLICATIONS catalogue.