The "four C" for diamonds

The internationally recognised "4 Cs" were developed by the GIA and are used for pricing diamonds. They reliably define the quality of a diamond.


A carat consists of 100 points. Thus the weight of a Diamond of 25 points corresponds to 1/4 or 0.25 carats. Good Carat scales show a very accurate weight to one thousandth of a Carat.

At the beginning of the twentieth century the carat weight of diamonds was adapted to the metric system and is now standardised internationally for diamonds, as is the 10-fold magnifying glass magnification for determining purity and the reference stones for grading the colour of a diamond.

Within small tolerances, the diamond is a standardised form which is ground according to mathematically fixed surface and angle dimensions. The weight and size of the diamond are predictably dependent on each other, so that the weight can be deduced from the size (diameter) and vice versa.

Originally the carat was the weight of a dried seed of the carob tree (Ceratonia siliqua). The weight of the seed is approx. 0.2 grams, which corresponds to approx. 1 carat for diamonds.


The purity of a diamond is determined with a magnifying glass at 10x magnification. "Magnifying glass clean" means: Without recognisable inner characteristics with the diamond. The P2 and P3 purity grades of a Diamond are no longer determined by the magnifying glass, but by the naked eye.

Inner characteristics of the diamond can help to shape the individuality of a diamond. The beauty of the diamond (colour effect) and the uniqueness of the diamond depend very much on the influence of internal characteristics.


no visible inclusions at 10x magnification


very very slight
very difficult to detect inclusions


very very slight
very difficult to detect inclusions


very slight
hard to spot inclusions


very slight
hard to spot inclusions


slightly imperfect
easily recognisable inclusions at 10x magnification


slightly imperfect
easily recognisable inclusions


very easily recognisable inclusions


inclusions visible to the naked eye


inclusions easily visible to the naked eye


The quality of the cut assesses the cut and the proportions of the diamond. These factors determine to a large extent the life - fire and brilliance - of a diamond.

Both the number of facets and their numerical distribution on the upper and lower parts as well as their symmetrical and size-related arrangement, and their angles to the roundness plane are of fundamental importance, as is the ratio of upper to lower part, from panel size to upper part height.


Diamonds that seem colourless to the untrained eye can be divided into different colour classes by the expert:
GIA Designation (CIBJO) Old designation
Superfine White+
Highly fine white
Fine White+
Top Wesselton
Fine White
Top Wesselton
Lightly tinted white+
Top Crystal
Lightly tinted white
Top Crystal
Tinted White+
Tinted White
Tinted 1
Top Cape
Tinted 2

This is one of the most important aspects in the classification of diamonds. The colour of the diamond contributes to its beauty and determines its price. Diamond crystals are usually colourless. The colour characteristics vary from place to place.

Fancy Diamonds

Intensively coloured diamonds are extremely rare. The colour of the diamond comes from its few impurities, such as nitrogen, iron magnesium, silicon, etc..

The occurrence of coloured diamonds ranges from the very rare and exceptional transparent blue-white, to yellowish tint, and from faint brown to a very dark brown colour.

A diamond with an attractive natural colour is a fancy diamond. Diamonds can occur in any colour, such as violet, pink, olive-green, apple green, yellow-green, cream, metallic, gold, brown, light yellow, orange-brown, blue-black, champagne, sapphire-blue, etc. colour descriptions such as matt, extravagant light, extravagant, and extravagant intensive serve to evaluate the diamond. The degree of emphasis of each perceived colour is attributed to saturation.

Diamonds which are absolutely free of any colour, flaw and deficiency, cracks, and scratches are rated very highly.

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