Blesq Diamonds
8 March 2019

Diamond Price & Quality Determination: The Famous «4C’s»

We’d like to share our passion and expertise for diamonds with you, which is why we’ve created the Blesq diamonds blog – read on for gripping tales and exciting news about the most precious gemstone on Earth.

The “4Cs” in detail

The GIA (Geomological Institute of America) – founded by diamond trader Robert M. Shipley – developed the “4Cs of diamond quality” in the 1940s. The famous four Cs are Carat, Color, Clarity (Purity), and Cut. Since this system was as simple as it is ingenious, it quickly established itself as the global and still effective method for determining a diamond’s quality and value. The “4Cs” guarantee more security for buyers and sellers – as well as more transparency and traceability on the diamond market.
Fundamentally interdependent, a diamond with a great amount of carat weight, for example, can lose value due to a cut of inferior quality.

Carat – the weight of a diamond

A carat is a unit of measurement used to measure the weight of diamonds and all other gemstones; where one carat (ct.) corresponds to 0.2 grams. A diamond with one carat is therefore worth more than a half carat (0.1 gram). Merchants and jewellers express carat over a 100 point scale, for example, a 0.25 carat diamond is equivalent to 25 points.

Color – the color of a diamond

Most jewelry diamonds have nuances from white/colorless to yellow. A GIA scale categorizes them from “D” for colorless and especially valuable to “Z” for yellow and less valuable.

Dyes are based on a wide variety of materials that have been involved in the process of creation. Colours such as blue, green and pink are very rare and can increase the value considerably. The respective colouring is classified from “Faint”, for weak and less valuable, to “Fancy”, for particularly intensive and valuable. Famous examples are the “Dresdner Grüne Diamant” or the “Blaue Wittelsbacher”.

Clarity – the purity of a diamond

The purity of a diamond determines how much light it can reflect. Similar to colorations, deep
inclusions can be traced back to events in the carbon phase at birth; the smallest material particles, so-called “spots”. Veils or turbidities, which are usually less intense, are called “clouds”. There are also “feathers”: molecular breaks in the diamond structure and they are the most frequently occurring flaws. Strong inclusions usually reduce the fire and thus the value of a diamond.

Clarity is determined under 10x magnification, but in determining the price, it is also important that the diamond is eye-clean despite inclusions.

Cut – the cut of a diamond

The cut is not only the most important feature to ignite the fire of a diamond, it is also the only point where man has contstant & continuous influence besides the extraction of the gemstone. Diamond cutting is a highly demanding task between art and science.

The edges and facets must be cut to absolute perfection. For grandiose brilliance, the rough diamond must be cut beforehand to see which cut produces as much material and character as possible. For the famous fire decisively determines the financial value of, and emotional connection to, a diamond.