They say that beauty is in the eye of the beholder; this is more than true of diamonds. For example, the smallest stone, given with love, is priceless to its recipient. But when you’re in the business of buying and selling diamond jewelry, you need metrics that are much more concrete. Beauty may be subjective, but value and worth requires harder numbers.This is where diamond grading comes in.

Understanding The Different Diamond Grades | K. Rosengart

GIA, an independent organization dedicated to educating and protecting the diamond-purchasing public, established a grading system in the 1950s. Used by professionals worldwide, GIA’s grading system examines the four Cs and assigns ratings so you know exactly what you are buying.

GIA Grading

Note: As yet, GIA does not grade melee diamonds. Given their small size, it is cost-prohibitive. That said, when purchasing these “mini” stones, opt for a reputable dealer to ensure you are maximizing your investment. Melee can make or break your profit margins.

Now, then, let’s dig into grading:


We’ll start here because it’s the most concrete area of grading. Diamonds are sold by weight, and diamonds are weighed to a thousandth (0.001) of a carat and rounded to the nearest hundredth. The difference of a few hundredths can mean hundreds or even thousands of dollars, which is why precision is the name of the game here.

Carat is just one grading factor; other influences - particularly cut - make an even bigger impact on the appearance of a diamond. So when it comes to purchasing either raw diamonds or finished pieces, keep in mind that carat is really just the beginning.


Diamonds come in all shapes, sizes, and colors. Colorless are the most rare, and the most sought-after. Thus, they’re the most valuable. GIA uses “master stones” against which to grade diamonds. These are stones of known color, and experts compare stones to these benchmarks to establish their color rating.

GIA uses a D-Z scale based on tone and saturation:

D-F: colorless

G-J: near colorless

K-M: faint

N-R: very light

S-Z: light

What about florescence? When exposed to UV light, about a quarter to a third of diamonds emit a visible light called fluorescence. Most of the time, it has a blue hue. Does this affect the diamond’s color? The short answer is no. As a buyer, you will notice no difference in quality or appearance in stones that emit fluorescence.

The slightly longer answer is that fluorescence could impact price. If you have a diamond that tends towards a yellow tone, blue fluorescence could make it appear whiter. On the other hand, if the fluorescence is too strong, it can make the stone appear cloudy or oily. Just another factor to consider when buying diamonds!


Perfection is unattainable - but it’s a goal we are forever chasing. Even diamonds, one of the most valuable substances on earth, are not perfect. They contain inclusions (internal features) and blemishes (irregularities on the surface, such as nicks and scratches). Clarity is the relative lack of inclusions and blemishes.

GIA’s clarity scale runs from flawless to I₃:

  • Flawless
  • Internally Flawless
  • VVS₁ - VVS₂: very very slightly included
  • VS₁ - VS₂: very slightly included
  • S₁- S₂: slightly included
  • I₁, I₂, I₃: included

Clarity is a complex factor to grade because no two stones are the same, and some imperfections have less of an impact. For example, an inclusion on the side of a stone does not influence value as much as the same inclusion if it were located directly under the table.

When it comes to clarity, certain settings help disguise imperfections. For example, if a stone has an inclusion on the side, a bezel setting can hide it. A diamond with an imperfection can be used as a star of a stunning piece.


Many consider cut the most important of the 4Cs. It refers to the diamond’s proportions, symmetry, and polish. These factors influence how light interacts with the facets and overall brilliance. A well-cut diamond is fiercely beautiful, and quite valuable. If there’s a choice between bigger carat or better cut, going with better cut is always smart.

GIA assigns a rating of Excellent, Very Good, Good, Fair, and Poor. To get there, their experts look at a variety of factors, such as how white light reflects from the stone, fire, scintillation, weight relative to diameter, girdle thickness, facet symmetry, quality of the facet polish, etc.

Best practice: go with the highest cut grade you can afford, even if you sacrifice in terms of the other three C’s.

Buying diamonds is a balancing act: you have to take your grading report through the lens of what is most important to your customers and to your business. It can be confusing or overwhelming - unless you have an expert on your side. Our diamond services include ensuring you source materials with the most advantageous ROI.

Melee Diamond Buying Guide | K. Rosengart