The 4 C’s of Diamond Grading: The Secret to Scoring the Perfect Diamond


When you’re choosing a diamond, either loose or pre-set in a piece of jewelry, you may have heard the term “4 C’s,” and wondered what that term means. The 4 C’s refers to the four qualities that determine how beautiful a diamond is. Color, cut, clarity, and carat are those qualities, but even with that, you may not know the details that go into them.

Here at Smyth Jewelers, we strive to bring our diamond expertise to our customers; read on to learn more about the 4 C’s and diamond education!

Diamond Color

People enjoy when white diamonds are as clear as possible, so that the diamond’s fiery rainbow of color can be better appreciated. While diamonds are, in a chemical context, made purely of the element carbon, it must be remembered that diamonds are formed randomly in nature, meaning that they can include foreign materials. The most common material is nitrogen, which gives diamonds a brown or yellow color.

The GIA has developed a D-Z scale for scoring white diamonds’ color, with “D” representing completely colorless diamonds, and “Z” reserved for extremely yellow-tinted stones. Do remember, though, that once a diamond’s yellowness passes the “Z” mark, it’s labeled as “fancy” and GIA offers a different grading scale for classifying it.

Diamond Clarity

Let’s say you’ve brought in an engagement ring for appraisal, and the GIA-certified appraiser tells you that your diamond is “very slightly included.” What does that mean?

Since diamonds, as we established, are grown randomly in the Earth, they can have crystal imperfections (known as feathering, cracks, bubbles, and voids) or solid material inside them. Silica, iron, and even small garnet crystals can be trapped inside the lattice of a diamond during its formation, changing the clarity—or clearness—of the stone.

When your appraiser says the diamond is very slightly included, the term for it is SI1 or SI2, which are two marks on the GIA scale of clarity, which goes from “FL,” which is flawless under 10x magnification; to “I3,” which is clearly included to the naked eye.

ring on rock

Diamond Cut

You may be familiar with reading the word “cut” when you’re searching for our wedding bands and engagement rings, but even though diamonds are referred to as things like “round-cut” or “princess-cut,” that largely refers to the shape of the diamond. The cut refers to the proportions of the crown, girdle, and pavilion of a diamond. Diamantaires use complex math and an in-depth knowledge of physics to maximize a diamond’s inner reflectivity, ideally making sure that your stone doesn’t lose light, have dark spots, or have weak fire.

The GIA rating scale for cut takes into consideration the ideal proportions for each shape of diamond to make sure that a buyer is getting a stone that’s had passion and craftsmanship put into it. Ranging from “excellent” to “poor,” the scale allows a clear grading method for the geometry of a diamond.

Diamond Carat Weight

Carat is slightly different than the other C’s, because it doesn’t rate the quality of a diamond. Rather, “carat” is the weight of a diamond. One carat is 0.2 grams, and each carat can be divided into 100 points. So, if you hear that your diamond is 2.51 carats, its weight is equivalent to 0.502 grams. Many people assume that carat is synonymous with size, but that’s not necessarily true! A tightly packed diamond like a princess-cut or round-cut will appear smaller than a long diamond of similar carat weight.

If you’re interested in learning more about diamonds, particularly the ones we offer at Smyth Jewelers, call us at 410-252-6666 or visit our Timonium, Annapolis, or Ellicott City, Maryland showrooms!

TIMONIUM  (410) 252-6666

2020 York Rd.
Timonium, Maryland 21093

Monday-Saturday 10-6

Closed Sunday

ANNAPOLIS  |  (443) 321-0300

Annapolis Town Center
1915 Towne Centre Blvd
Annapolis, Maryland 21401

Monday-Saturday 10-6

Sunday 12-5

ELLICOTT CITY |  (410) 461-4044

Turf Valley Towne Square
11089 Resort Road #200
Ellicott City, Maryland 21042 

Monday-Saturday 10-6

Closed Sunday