DIAMOND GRADING
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The key to value in gemstones is beauty and rarity. In an effort to "quantify" beauty, and to make it less subjective, a grading system was developed. We now call it the "4 C's".

The four C's are:

  1. Color
  2. Clarity
  3. Cut
  4. Carat Weight

All things being equal, the gems having a better grade in any of these four categories will be more beautiful, and therefore more valuable. (This applies to colored gems as well as diamonds.) Of two of the same kind of gems that have the same color, cut, and weight, the one with the better clarity grade will be more beautiful.

In colored gems, the more intense color is more valuable. In diamonds, the less body color, the more valuable. This has to do with rarity more than with beauty, and intense fancy colors in natural diamonds are more valuable.

The most common colors in diamonds are yellow, brown, and gray. These are usually not attractive in the light tones.

(The following explanation is condensed for space and comprehension. It is not complete and is not meant to substitute for a full explanation and understanding of these bodies of knowledge.)

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1) Color

The GIA (Gemological Institute of America) color grading scale for diamonds begins at D, which is considered completely colorless. (This is usually called "white", but milk is white.) D, E, and F colors are extremely fine, colorless grades. It is difficult to discern any body color in these gems without proper lighting, a white background, and master stones against which to compare them. G, H, and I are very good colors found in most fine grades of jewelry. In these grades, if someone is looking carefully they may discern a very light body tint. J, K, and L are grades in which color begins to show more plainly and value is lower. These gems will still look nice if set into yellow gold which will mask the body color. Some people prefer diamonds in these higher color ranges and they are called "warm" colors.

As the alphabet continues, value drops until we get to the letter Z. After Z, the colors are called "Fancy" and can become very expensive.

2) Clarity

The GIA clarity scale begins with I3 and goes up to Internally Flawless. Starting at the top and going down we have:

3) Cut

Cut does not refer to the shape of the gem, but rather to how well its shape is crafted. Its symmetry on three axes and the various angles of the top and bottom determine how well a gem is cut. If the angles are properly set, the gem will be more brilliant. The light that comes out of the front of the diamond is the same light that came in the front. Light doesn't come from the back of a diamond. Cutting the angles properly assures that light will be reflected properly so it can dazzle the eyes.

The angles are determined by studying the refractive index of a gem. This has to do with how much light bends when it enters a gem and it is crucial to brilliance. Each gem has a different refractive index.

4) Carat Weight

If all of the other factors are equal, the larger gem will be worth more than the smaller one. This also has to do with rarity; it is much harder to find a large piece of "perfection" than a small one. In diamonds, not only is the price higher for a larger gem (simple math) but the per carat price is higher too.


Those are the four C's and the add up to the fifth C: Cost.

Barry Nicholls, the owner of Paradise Jewelry, teaches a class called Diamonds and Gems (click here for full text) as part of adult education at the nearby high school.
If we can help you
or answer any other questions,
please E-mail us at Beary3@aol.com
or give us a call at (941) 591-2645
Write us at
Paradise Jewelry
5455 Airport Road N.
Naples, Fl. 34109


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