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Assessment Criteria Of Diamonds


There are four basic parameters for evaluating and certifying diamonds which have a significant influence on the price of diamonds.

  • Carat
  • Color
  • Clarity
  • Cut


The weight of a diamond is always given in carats and the international abbreviation, ct is used. The weight is indicated in certificates with 2 decimal places. Measurement is done with an accuracy of 3 decimal places. The second decimal place can only be rounded up if the third decimal place is 9.

carat mm
0.05 2.5
0.10 3.0
0.20 3.8
0.25 4.1
0.30 4.5
0.40 4.8
0.50 5.2
0.70 5.8
0.90 6.3
1.00 6.5
1.25 6.9
1.50 7.4
2.00 8.2


The diamond is the only gemstone that occurs in all shades of color but the most common colors (after cutting) are from white to yellow. An international rating system from “D” to “Z” was developed for these basic colors. The whiter the shade of the stone, the closer the mark of the stone is to the beginning of the alphabet.

Color specification must be performed by experienced professionals by using a set of sample stones and comparing them with a given stone. Carefully controlled lighting conditions must be used for example, normalized light of 5000/5500 K (D55) and a standard procedure for the classification of the examined stone to the right color grade.

D Exceptional white +
E Exceptional white
F Rare white +
G Rare white
H White
Slightly tinted white
Tinted white
Tinted color


The clarity is given by the number of foreign substances included in the diamond. Such in-homogeneities may be internal in which case they are called inclusions (black “carbon“, white “ice“, cracks, etc.). They arise during particular phases of crystal formation. Further, defects may be of an external character (scratches, extra facets), which may be caused through cutting and polishing or defects that couldn´t be removed during processing. The size and the placing of these inclusions are key factors for the process of grading clarity. A standard diamond grading loupe of 10x magnification is used for measuring clarity.

The International Scale of Diamond Clarity

  • FL – FLAWLESS Transparent without any inclusions.
  • IF – INTERNALLY FLAWLESS – If the diamond is transparent without any visible (under 10x zoom) inclusions, it is loupe-clean
  • VVS – VERY VERY SMALL INCLUSIONS Very very small inclusions hardly detected (under 10x zoom) by a diamond grading loupe.
  • VS – VERY SMALL INCLUSIONS Very small inclusions hardly detected (under 10x zoom) by a diamond grading loupe.
  • SI – SMALL INCLUSIONS Small inclusions easily found by a diamond grading loupe but invisible on naked eye from the table side.
  • Other degrees of the grading VVS, VS and SI and their two subcategories can be used only for grading of 0.47 ct diamonds and bigger. Using terms like “pure”, “pure to eye”, “commercial pure” or other confusing expressions are not allowed.
  • P – IMPERFECT ( I )
  • P1 – Medium inclusions which can be easily located by a loupe but hardly seen on naked eye.
  • P2 – A big number of large inclusions easily detected on naked eye.
  • P3 – Big and numerous inclusions easily detected on naked eye and influencing the brightness of the diamond.


Cut of gem is defined by type and shape.


Most common cut is round brilliant cut. Round mean shape and brilliant type of cut. brilliant cut is typical by triangular (star) facet.

From top

Beginning of modern cut was started in 1919. In this year Marcel Tolkowsky published the specifications of what would later be called the American Standard (also known as the American Ideal Cut, Tolkowsky cut, and Tolkowsky Brilliant), which is the diamond-cutting benchmark in North America. It was derived from mathematical calculations that considered both brilliance and fire of the stone.

From side

Cut referes to the symmetry, proportioning and polish of a diamond.

Stone cut categories – Excellent, Very Good, Good, Fair, and Poor.

From bottom

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