Diamond Ring Grading: The 4 Cs
If you’ve shopped for diamonds online(*1), you’ve probably noticed some of the data that comes up in search results, usually in the form of numbers or abbreviations like “H,” “J,” or “VS2,” or cryptic terms like “Ideal” or “Premium.” Diamond rings, and the diamonds used in them, are graded according to four major criteria. These criteria are called “cut,” “clarity,” “color,” and “carats.”
While the ratings and the ways in which they’re expressed can be confusing to the ordinary consumer, they are very important, as they have a huge influence on the market value and sale price(*2) of a diamond. You’ve probably noticed that some diamonds are relatively affordable, while others can be valued at tens of thousands to even millions of dollars; this is, in essence, entirely because of differences in the “four Cs.”
If you’re in the market for diamonds, it’s worthwhile to take the time necessary to learn about these variables, what they mean, and exactly what sort of impact they can have upon diamond valuation. Quite simply, the difference between having this knowledge and not having it can mean the difference between understanding what a good price is for a diamond, and making a mistake.
In diamond grading terms, “cut” refers to the overall reflectiveness and brilliance of a diamond. Cut in this respect is not to be confused with the different standard shapes of a diamond, which themselves are commonly referred to as “cuts,” such as the round brilliant cut or the Princess cut.
Diamond Ring Grading: The 4 Cs
A diamond’s cut rating has a very significant influence on its price. Unfortunately, cut is also the most difficult of the grading criteria for non-experts to get a handle on, and even among professionals, it can sometimes seem to be an almost subjective measure. The different diamond certification authorities (more on them later) each take different approaches to determining and expressing the quality of a diamond’s cut. Vendors sometimes try to simplify these grades; the cut grades you’re most likely to see on online diamond retailers’ websites are, in order from best to worst: Ideal, Premium, Very Good, Good, Fair, and Poor; so, diamonds with an Ideal cut rating are the most brilliant, while diamonds with a Poor grade will be relatively dull-looking.
The clarity grade is somewhat easier to understand. Clarity refers specifically to the lack of visible flaws both on the surface of a diamond and on its interior. Flaws on the outside of a diamond are commonly called “blemishes,” while interior flaws are called “inclusions.”
Clarity grades are expressed as follows: F, for “Flawless;” IF, for “Internally Flawless,” for diamonds with no inclusions but slight exterior flaws; VVS1 and VVS2, for “Very Very Slightly Included,” meaning possible flaws to the outside and tiny inclusions which are barely visible under magnification; VS1 and VS2, for “Very Slightly Included,” for flaws which are slightly more visible under magnification; SI1 and SI2, for “Slightly Included,” meaning that the flaws are relatively easy to see under magnification; and I1, I2 and I3, for “Included,” in which cases the inclusions may be visible to the naked eye.
A diamond’s color rating denotes the extent to which coloration is visible within the diamond. In the majority of cases, the less visible the color is, the more attractive the diamond is thought to be. The color rating scale starts at D and goes to X, with D-grade diamonds being colorless, and X-grade diamonds having a clearly visible yellowish hue.
The degree to which color is visible can also vary depending on the shape of the diamond. Truly colorless diamonds are extremely rare and thus very, very expensive. At the same time, in the middle ranges of color grades, the difference to the naked eye can be difficult to discern, and so the price differences can be accordingly subtle.
Diamonds as far down as the I color rating can be virtually colorless to the naked eye. Note that the color rating scale does not apply in the same way to naturally colored diamonds, such as pink or blue diamonds. These diamonds are actually considered more valuable if the coloration is stronger.
Carats are the unit of measurement used to express the actual weight of a diamond. This is the most straightforward of the four Cs, yet it also has the most obvious impact on the price of a diamond. A 5-carat diamond will always be significantly more expensive than a 3-carat diamond, even if the 5-carat diamond rates more poorly in every other respect.
Due to budget constraints, most consumers wouldn’t even consider buying a diamond over one carat. If you want to buy a diamond with the best possible overall quality at the best possible price, it’s a good idea to focus more on the other grading criteria, even though the differences there can be more difficult to discern in some ways.
Most diamonds on the market are rated in these ways. However, the ratings aren’t just made up by vendors. In order to maintain the integrity of the market, vendors rely on independent certifying organizations to assign grades to diamonds. The two biggest and most respected authorities are the Gemological Institute of America (GIA) and the American Gem Society (AGS). Reputable online diamond retailers, such as James Allen(*3), Mondera(*4), and Blue Nile(*5), will only sell diamonds certified by respected bodies. This is your guarantee that the properties of a diamond are as advertised.
*1 – “Online Diamond Buying Guide” article
*2 – “Diamond Prices” article
*3, 4, 5 – jamesallen.com, mondera.com and bluenile.com reviews respectively