A diamond’s quality is assessed on the basis of the 4C rule – which takes its name from the initial letters of words: color, quality, cut and carat. These four qualities comprise the valuation of a stone and help ascertain its rarity. Thanks to the cooperation between Mart Diamonds with the best institutes in the world, our diamonds have complete documentation which transparently explains the qualities necessary for the appraisal of the stones.


The value of a diamond decreases
along with the presence of the
yellow hue in a stone.




The clarity of a diamond is assessed on the strength of two elements: inclusions (the characteristics of the inside of a diamond) and blemishes (the outside marks).



A cut is the only quality of a diamond that’s determined by human influence.

How much of a shine will a diamond have and how good its cut will be depend entirely on the cutter’s craft. The assessment of a cut is formed on the basis of detailed analysis of stone’s proportions as well as cut’s finish, including its symmetry and polish. Lack of symmetry and poor proportions result in improper light refraction which translates to poor brilliance.

Infografiki przedstawiające kształt diamentów

Depending on the natural shape of a rough stone, a cutter has to choose an appropriate cut that will not only highlight the diamond’s shine but also allow to minimize the loss of the material. The most popular cut is, of course, the brilliant, considered by many to be the masterpiece of cutters’ craft.


Mass of diamonds and other gemstones is expressed in metric carats. 1ct = 0,2g

A diamond’s mass is related to its diameter and height. Assuming the correct values for brilliant cut stones, their weight can be estimated at:

2,5mm x 1,5mm = 0,05ct
5mm x 3,1mm  = 0,050ct
6,5mm x 3,9mm  = 1,00ct

These metrics and the relationship between them may change depending on the type of cut. The mass of a stone is also influenced by the thickness of its girdle. Two stones of the same height and diameter differing in girdle’s thickness can have a totally different mass. The exact weight of a diamond can be only determined through a scrupulous and professional appraisal.