Understanding Diamond “4 C’s”

Diamond Carat Weight

Diamonds are sold by the carat. One carat = 0.20 grams, or 1/5 th of a gram. Wholesale prices are normally quoted per carat, not by the gem. It is a quick easy reference for comparison.

Certain diamond sizes usually command higher prices per carat .. break points, so to speak. A diamond of .5 or .51 carats will be worth more per carat than an equal quality stone of .49 carats. Other break points are 1 carat, 2 carats, etc … and prices increase exponentially.

Diamond Clarity

10X Triplet Loupe

Clarity describes the absence or presence of included crystals, voids, cracks, fissures, etc. which might be present in a diamond; observable by a trained individual with normal eyesight while using a 10X loupe. The size, location, distraction and number of the characteristics are compared to a set of established industry standards.

I-F (internally flawless) is the top modern grade. “Declass” is .. well, junk! We recommend that you not consider any grade below VS unless it is for novelty jewelry.

Not every characteristic observed in a diamond distracts from the stone’s acceptability to certain individuals. Nicely colored included crystals and crystal growth features that have created internal spectral arrays are examples of “imperfections” that give a diamond a unique personality.

Aside: I once saw an emerald cut diamond with a tiny green crystal inside. It was beautifully unique.

Another emerald cut had formed with a small area of internal stress. It had a tiny rainbow of spectral colors inside. To me, it was a remarkable gemstone.

Diamond Color

For non-fancy diamonds white aka colorless is considered ideal. Color is determined in the grading lab by using a master set of stones with color grades established by a standards lab. Diamonds are color-graded pavilion up … upside down, so to speak.

Grading starts with “D” being considered colorless. The variations between “D” and “E” are so minor that only an expert with good color balanced eyesight and with proper lighting in a correct environment can see the gradation.

Diamond color grades tend to be stated in sets of 3. ”D-E-F” is the whitest grade.

Yellow and brown are considered least desirable, with gray next and blue better.

Never attempt grading a diamond in a mounting. Metal colors — or hidden color-aids cannot be eliminated.

Also: the slightest mark on the girdle of a diamond with a blue felt tip pen can mask yellow and improve the apparent color grade of the diamond significantly.

Diamond Cut

Cut may be the most important of the C factors. A well fashioned diamond should be symmetrical, proportioned to take advantage of the optical properties of diamond, and polished to a high quality standard.

Symmetry, either 2 way symmetry (heart, pear); or 4 way symmetry (round, oval, emerald, marquise, cushion, radiant) is a crucial factor in displaying the beauty of a diamond.

Diamond Proportion

Correct diamond proportion is the result of good cutting. Proportion makes a diamond do what it is supposed to do; direct the maximum amount of light entering the gem toward the eye of the observer.

Diamond characteristics are determined by nature and physics, not by marketing hype. Significant deviation from certain angular proportions will result in a less appealing gem.

  • Spread = dead. In a gem cut too wide for it’s depth, light will leak out the pavilion and dull the gem’s appearance.
  • Facet junctions should be crisp, not “rolled”.
  • Facet corners should meet / align perfectly.
  • Girdles should be straight rather than wavy. An uneven girdle signals a poor cut.
  • Girdles should not be overly thin or could reduce the diamond’s durability.
  • Overly Thick girdles are wasting the crystal’s potential, and wasting your $$$. Thick girdles will result in smaller appearing diamond for the same carat weight
  • A large culet may be a way of reducing color. Large culets not only change a diamond’s appearance, they may signal a crystal with a higher color range than observed.
  • Exceptions might include cutting techniques to idealize proportions … unless you need a special viewer to see the features. Do you really want to carry around a polariscope to show people the unique features of “your” diamond?
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