What are the "4 C's"?
Each diamond can be assigned individual characteristics – similar to a human fingerprint. These characteristics are known as the 4Cs, which stand for Carat (weight), Clarity (purity), Cut (cut quality), and Color. They serve as globally recognized standards for assessing the quality of diamonds.
For example, the size of a stone alone says nothing about its value. A large stone that has imperfections (also known as inclusions) is less valuable than a small stone that is flawless.
These evaluation criteria apply to mined diamonds as well as to lab-grown diamonds, so-called Lab Grown Diamonds, which we use for our jewelry.
Want to learn more about the difference between traditional mined diamonds and innovative lab-grown diamonds? You'll find more information in this blog post.
The definition of the C's
CARAT / WEIGHT
Carat, or simply "karat," indicates the weight of a diamond, with 1 carat equaling 0.2 grams. The weight allows for a rough estimate of the stone's size, as diamonds of the same cut have nearly identical proportions. Certification is also possible, but it is only worthwhile for stones weighing 0.23 grams or more, as the cost of evaluation becomes disproportionate for smaller stones. It is crucial that the institute evaluating the diamonds is independent, neutral, and professional to accurately determine the diamond's quality and, consequently, its value. Recognized gemological institutes include the GIA (Gemological Institute of America) and its European counterpart, the HRD (Hoge Raad voor Diamant), which means High Council of Diamonds .
CLARITY / PURITY
The purity grade is defined by the term "clarity." During the formation of diamonds, a naturally occurring chemical process involving extremely high temperatures and the interaction of carbon atoms, other minerals can become trapped within the diamond, disrupting its structure and making it appear less clear. These inclusions reduce the value of a stone. Absolutely pure diamonds are extremely rare and therefore all the more valuable.
The GIA has defined a clarity scale that includes 11 levels, with most diamonds falling into the categories VS (very slightly included) or SI (slightly included).
- Flawless (FL) = Perfectly clear: No inclusions or blemishes are visible at 10x magnification.
- Internally Flawless (IF) = Internally flawless: no inclusions; imperfections are only visible under 10x magnification
- Very, Very Slightly Included (VVS1 and VVS2) = Very, very slightly included: inclusions are difficult to see under 10x magnification
- Very Slightly Included (VS1 and VS2) = Very slightly included: Inclusions are minor, but easier to see under 10x magnification
- Slightly Included (SI1 and SI2) = Slightly included: Inclusions are visible under 10x magnification
- Included (I1, I2 and I3) = Included: Inclusions are visible under 10x magnification and with the naked eye and can affect the transparency and brilliance of the diamond.
CUT / FINISH QUALITY
The cut quality is the most important characteristic for determining a diamond's brilliance. It's important to note that it's not the shape of the cut (round, square, princess cut, etc.) that's being evaluated, but rather the actual quality of the cut itself. When the diamond's height and width are in the correct proportion, the stone reflects light back towards the viewer, creating the desired "inner fire"—a hallmark of a very well-cut diamond. Poorly cut diamonds sparkle less because even small irregularities cause them to scatter light in all directions. The arrangement of the facets is also crucial—when they are properly aligned, the diamond presents a harmonious appearance when viewed from above. The subsequent polishing, which is usually only visible under a magnifying glass, should not be overlooked either—the fewer polishing marks, the better; ideally, none should be visible at all.
Although this characteristic focuses on the quality of the cut, the cut shapes should not be completely disregarded. Among the most popular faceted cuts are the baguette cut, the brilliant cut, the heart cut, the oval cut, the cushion cut, the princess cut, the emerald cut, and finally, the pear cut.
COLOR
Color is one of the most important factors in determining quality. A distinction is made between colorless diamonds and diamonds with a yellow tint. Colorless (or ultra-fine white) diamonds represent the highest quality and are therefore the most valuable. Here, too, there is an internationally recognized grading scale developed by the GIA. It ranges from top quality (color D) to the noticeably tinted shade Z. In a somewhat broader classification, the individual letters are grouped into six categories:
Ultra-fine white (D and E), fine white (F and G), white (H), slightly tinted white (I and J), tinted white (K and L); the remaining levels up to Z are designated tinted or distinct tint.
However, there are also diamonds that exhibit completely different colors – namely pink, red, yellow, green, brown, or black. These are known as "fancy diamonds," are very rare, and in most cases more expensive than white diamonds. Their quality is assessed using entirely different evaluation criteria.
Sources (as of August 26, 2022)
https://www.deutscher-diamant-club.de/info/diamanten-qualitaetskriterien.php
https://gemmologie.ch/de/gemmologie/4c/
https://www.steine-und-minerale.de/artikel.php?topic=5&ID=115
https://deutsche-schmuck-und-uhren.de/wp-content/uploads/2020/08/DiamantflyerA5.pdf