The main rules of 4C
Grading diamonds based on professional expertise, grew in response to the rapidly growing market for diamonds: the GIA (Gemmological Institute of America) established the Gem Trade Laboratory in the USA in 1935, the Gubelin laboratory in Lucerne issuing certificates since 1940, in 1961 the international organization, CIBJO was established to join producers and sellers of precious stones, jewels and pearls, and in 1976 the Dutch Department of Certification established the Diamond high council (Hoge Raad voor Diamanten-HRD).
There are four basic parameters for evaluating and certifying diamonds: cut, carat, clarity and colour which have a significant influence on the price of diamonds.
These parameters are called the 4C.
Other parameters that can be in certificates are: size, fluorescence, internal and external characteristics, etc.
To better understand the evaluation of diamonds, we recommend the world-renown book by Verena Pagel Theisen “Diamond Grading ABC” which was translated into Czech by Engr. Ladislav Klaboch: Diamanty: Příručka hodnocení diamantů.