Diamond Grading Report

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. Stones under 0.30ct are not graded.

For stones over 0.30ct, 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 grade:

The colour grade of a diamond is defined by comparing it with a CIBJO masterstone set (C2) and with two additional SSEF masterstone sets for better accuracy. The colour grades issued on diamond reports are:

Clarity grade:

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

Cut grade:

The cut grade of a diamond depends on its symmetry, polish, proportions and girdle thickness.

 

Authentication of natural origin and colour:

The following scientific instrumentation are used routinely: FTIR (identification of diamond type), low temperature photoluminescence spectrometry (colour authenticity test), low temperature UV-Vis spectrometry (treatment detection).

Cut and shape are reported in accordance with the usual trade names.

Other items stated on SSEF 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, they 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 Diamonds.